﻿using System;
using System.Collections.Generic;

using System.Text;
using RoughJs.Helper;
using RoughJs.Error;

namespace RoughJs.Ast
{
    /// <summary>
    /// 2010-01-5 ----- 2010-01-29
    /// 陈曦 1.0
    /// Microsoft Public License (Ms-PL)
    ///This license governs use of the accompanying software. If you use the software, you accept this license. If you do not accept the license, do not use the software.
    ///1. Definitions
    ///The terms "reproduce," "reproduction," "derivative works," and "distribution" have the same meaning here as under U.S. copyright law.
    ///A "contribution" is the original software, or any additions or changes to the software.
    ///A "contributor" is any person that distributes its contribution under this license.
    ///"Licensed patents" are a contributor's patent claims that read directly on its contribution.
    ///2. Grant of Rights
    ///(A) Copyright Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, each contributor grants you a non-exclusive, worldwide, royalty-free copyright license to reproduce its contribution, prepare derivative works of its contribution, and distribute its contribution or any derivative works that you create.
    ///(B) Patent Grant- Subject to the terms of this license, including the license conditions and limitations in section 3, each contributor grants you a non-exclusive, worldwide, royalty-free license under its licensed patents to make, have made, use, sell, offer for sale, import, and/or otherwise dispose of its contribution in the software or derivative works of the contribution in the software.
    ///3. Conditions and Limitations
    ///(A) No Trademark License- This license does not grant you rights to use any contributors' name, logo, or trademarks.
    ///(B) If you bring a patent claim against any contributor over patents that you claim are infringed by the software, your patent license from such contributor to the software ends automatically.
    ///(C) If you distribute any portion of the software, you must retain all copyright, patent, trademark, and attribution notices that are present in the software.
    ///(D) If you distribute any portion of the software in source code form, you may do so only under this license by including a complete copy of this license with your distribution. If you distribute any portion of the software in compiled or object code form, you may only do so under a license that complies with this license.
    ///(E) The software is licensed "as-is." You bear the risk of using it. The contributors give no express warranties, guarantees or conditions. You may have additional consumer rights under your local laws which this license cannot change. To the extent permitted under your local laws, the contributors exclude the implied warranties of merchantability, fitness for a particular purpose and non-infringement. 
    /// </summary>
    public class Interpreter : Evaluator
    {

        public class GeneratorState
        {
            public GeneratorState(int operation, Object value)
            {
                this.operation = operation;
                this.value = value;
            }
            public int operation;
            public Object value;
            public Exception returnedException;
        }



        private class ContinuationJump
        {


            public CallFrame capturedFrame;
            public CallFrame branchFrame;
            public Object result;
            public double resultDbl;

            public ContinuationJump(NativeContinuation c, CallFrame current)
            {
                this.capturedFrame = (CallFrame)c.getImplementation();
                if (this.capturedFrame == null || current == null)
                {
                    // Continuation and current execution does not share
                    // any frames if there is nothing to capture or
                    // if there is no currently executed frames
                    this.branchFrame = null;
                }
                else
                {
                    // Search for branch frame where parent frame chains starting
                    // from captured and current meet.
                    CallFrame chain1 = this.capturedFrame;
                    CallFrame chain2 = current;

                    // First work parents of chain1 or chain2 until the same
                    // frame depth.
                    int diff = chain1.frameIndex - chain2.frameIndex;
                    if (diff != 0)
                    {
                        if (diff < 0)
                        {
                            // swap to make sure that
                            // chain1.frameIndex > chain2.frameIndex and diff > 0
                            chain1 = current;
                            chain2 = this.capturedFrame;
                            diff = -diff;
                        }
                        do
                        {
                            chain1 = chain1.parentFrame;
                        } while (--diff != 0);
                        if (chain1.frameIndex != chain2.frameIndex) Kit.codeBug();
                    }

                    // Now walk parents in parallel until a shared frame is found
                    // or until the root is reached.
                    while (chain1 != chain2 && chain1 != null)
                    {
                        chain1 = chain1.parentFrame;
                        chain2 = chain2.parentFrame;
                    }

                    this.branchFrame = chain1;
                    if (this.branchFrame != null && !this.branchFrame.frozen)
                        Kit.codeBug();
                }
            }
        }


        private class CallFrame : ICloneable
        {

            public CallFrame parentFrame;
            // amount of stack frames before this one on the interpretation stack
            public int frameIndex;
            // If true indicates read-only frame that is a part of continuation
            public bool frozen;

            public InterpretedFunction fnOrScript;
            public InterpreterData idata;

            // Stack structure
            // stack[0 <= i < localShift]: arguments and local variables
            // stack[localShift <= i <= emptyStackTop]: used for local temporaries
            // stack[emptyStackTop < i < stack.Length]: stack data
            // sDbl[i]: if stack[i] is UniqueTag.DOUBLE_MARK, sDbl[i] holds the number value

            public Object[] stack;
            public int[] stackAttributes;
            public double[] sDbl;
            public CallFrame varSource; // defaults to this unless continuation frame
            public int localShift;
            public int emptyStackTop;

            public DebugFrame debuggerFrame;
            public bool useActivation;
            public bool isContinuationsTopFrame;

            public Scriptable thisObj;
            public Scriptable[] scriptRegExps;

            // The values that change during interpretation

            public Object result;
            public double resultDbl;
            public int pc;
            public int pcPrevBranch;
            public int pcSourceLineStart;
            public Scriptable scope;

            public int savedStackTop;
            public int savedCallOp;
            public Object throwable;

            public CallFrame cloneFrozen()
            {
                if (!frozen) Kit.codeBug();

                CallFrame copy;
                try
                {
                    copy = (CallFrame)Clone();
                }
                catch (Exception ex)
                {
                    throw new Exception();
                }

                // clone stack but keep varSource to point to values
                // from this frame to share variables.

                copy.stack = (object[])stack.Clone();
                copy.stackAttributes = (int[])stackAttributes.Clone();
                copy.sDbl = (double[])sDbl.Clone();

                copy.frozen = false;
                return copy;
            }

            #region ICloneable Members

            public object Clone()
            {
                return new CallFrame()
                {
                    parentFrame = this.parentFrame,
                    frameIndex = this.frameIndex,
                    frozen = this.frozen,
                    fnOrScript = this.fnOrScript,
                    idata = this.idata,
                    stack = this.stack,
                    stackAttributes = this.stackAttributes,
                    sDbl = this.sDbl,
                    varSource = this.varSource, // defaults to this unless continuation frame
                    localShift = this.localShift,
                    emptyStackTop = this.emptyStackTop,

                    debuggerFrame = this.debuggerFrame,
                    useActivation = this.useActivation,
                    isContinuationsTopFrame = this.isContinuationsTopFrame,

                    thisObj = this.thisObj,
                    scriptRegExps = this.scriptRegExps,

                    result = this.result,
                    resultDbl = this.resultDbl,
                    pc = this.pc,
                    pcPrevBranch = this.pcPrevBranch,
                    pcSourceLineStart = this.pcSourceLineStart,
                    scope = this.scope,

                    savedStackTop = this.savedStackTop,
                    savedCallOp = this.savedCallOp,
                    throwable = this.throwable

                };
            }

            #endregion
        }






        // Additional interpreter-specific codes

        private const int

    // 栈: ... value1 -> ... value1 value1
        Icode_DUP = -1,

    // 栈: ... value2 value1 -> ... value2 value1 value2 value1
        Icode_DUP2 = -2,

    // 栈: ... value2 value1 -> ... value1 value2
        Icode_SWAP = -3,

    // 栈: ... value1 -> ...
        Icode_POP = -4,

    // Store stack top into return register and then pop it
        Icode_POP_RESULT = -5,

    // To jump conditionally and pop additional stack value
        Icode_IFEQ_POP = -6,

    // various types of ++/--
        Icode_VAR_INC_DEC = -7,
        Icode_NAME_INC_DEC = -8,
        Icode_PROP_INC_DEC = -9,
        Icode_ELEM_INC_DEC = -10,
        Icode_REF_INC_DEC = -11,

    // load/save scope from/to local
        Icode_SCOPE_LOAD = -12,
        Icode_SCOPE_SAVE = -13,

        Icode_TYPEOFNAME = -14,

    // helper for function calls
        Icode_NAME_AND_THIS = -15,
        Icode_PROP_AND_THIS = -16,
        Icode_ELEM_AND_THIS = -17,
        Icode_VALUE_AND_THIS = -18,

    // Create closure object for nested functions
        Icode_CLOSURE_EXPR = -19,
        Icode_CLOSURE_STMT = -20,

    // Special calls
        Icode_CALLSPECIAL = -21,

    // To return undefined value
        Icode_RETUNDEF = -22,

    // Exception handling implementation
        Icode_GOSUB = -23,
        Icode_STARTSUB = -24,
        Icode_RETSUB = -25,

    // To indicating a line number change in icodes.
        Icode_LINE = -26,

    // To store shorts and ints inline
        Icode_SHORTNUMBER = -27,
        Icode_INTNUMBER = -28,

    // To create and populate array to hold values for [] and {} literals
        Icode_LITERAL_NEW = -29,
        Icode_LITERAL_SET = -30,

    // Array literal with skipped index like [1,,2]
        Icode_SPARE_ARRAYLIT = -31,

    // Load index register to prepare for the following index operation
        Icode_REG_IND_C0 = -32,
        Icode_REG_IND_C1 = -33,
        Icode_REG_IND_C2 = -34,
        Icode_REG_IND_C3 = -35,
        Icode_REG_IND_C4 = -36,
        Icode_REG_IND_C5 = -37,
        Icode_REG_IND1 = -38,
        Icode_REG_IND2 = -39,
        Icode_REG_IND4 = -40,

    // Load string register to prepare for the following string operation
        Icode_REG_STR_C0 = -41,
        Icode_REG_STR_C1 = -42,
        Icode_REG_STR_C2 = -43,
        Icode_REG_STR_C3 = -44,
        Icode_REG_STR1 = -45,
        Icode_REG_STR2 = -46,
        Icode_REG_STR4 = -47,

    // Version of getvar/setvar that read var index directly from bytecode
        Icode_GETVAR1 = -48,
        Icode_SETVAR1 = -49,

    // Load unefined
        Icode_UNDEF = -50,
        Icode_ZERO = -51,
        Icode_ONE = -52,

    // entrance and exit from .()
       Icode_ENTERDQ = -53,
       Icode_LEAVEDQ = -54,

       Icode_TAIL_CALL = -55,

    // Clear local to allow GC its context
       Icode_LOCAL_CLEAR = -56,

    // Literal get/set
       Icode_LITERAL_GETTER = -57,
       Icode_LITERAL_SETTER = -58,

    // const
       Icode_SETCONST = -59,
       Icode_SETCONSTVAR = -60,
       Icode_SETCONSTVAR1 = -61,

    // Generator opcodes (along with Token.YIELD)
       Icode_GENERATOR = -62,
       Icode_GENERATOR_END = -63,

       Icode_DEBUGGER = -64,

       Icode_UnDEFINED = -96,//Undefined 更新了一下原来的代码，这里加入了 null与undefined的比较,ECMA里面没有提到这两个值比较,请参看<<JavaScript高级程序设计>>的2.6.3 alert(null==undefined)的比较
            // Last icode
        MIN_ICODE = -96;


        private CompilerEnvirons compilerEnv;

        private bool itsInFunctionFlag;
        private bool itsInTryFlag;

        private InterpreterData itsData;
        private ScriptOrFnNode scriptOrFn;
        private int itsICodeTop;
        private int itsStackDepth;
        private int itsLineNumber;
        private int itsDoubleTableTop;
        private ObjToIntMap itsStrings = new ObjToIntMap(20);
        private int itsLocalTop;

        private static int MIN_LABEL_TABLE_SIZE = 32;
        private static int MIN_FIXUP_TABLE_SIZE = 40;
        private int[] itsLabelTable;
        private int itsLabelTableTop;
        // itsFixupTable[i] = (label_index << 32) | fixup_site
        private long[] itsFixupTable;
        private int itsFixupTableTop;
        private ObjArray itsLiteralIds = new ObjArray();

        private int itsExceptionTableTop;
        private static int EXCEPTION_TRY_START_SLOT = 0;
        private static int EXCEPTION_TRY_END_SLOT = 1;
        private static int EXCEPTION_HANDLER_SLOT = 2;
        private static int EXCEPTION_TYPE_SLOT = 3;
        private static int EXCEPTION_LOCAL_SLOT = 4;
        private static int EXCEPTION_SCOPE_SLOT = 5;
        // SLOT_SIZE: space for try start/end, handler, start, handler type,
        //            exception local and scope local
        private static int EXCEPTION_SLOT_SIZE = 6;

        // ECF_ or Expression Context Flags constants: for now only TAIL is available
        private static int ECF_TAIL = 1 << 0;


        private static int bytecodeSpan(int bytecode)
        {
            switch (bytecode)
            {
                case Token.THROW:
                case Token.YIELD:
                case Icode_GENERATOR:
                case Icode_GENERATOR_END:
                    // source line
                    return 1 + 2;

                case Icode_GOSUB:
                case Token.GOTO:
                case Token.IFEQ:
                case Token.IFNE:
                case Icode_IFEQ_POP:
                case Icode_LEAVEDQ:
                    // target pc offset
                    return 1 + 2;

                case Icode_CALLSPECIAL:
                    // call type
                    // is new
                    // line number
                    return 1 + 1 + 1 + 2;

                case Token.CATCH_SCOPE:
                    // scope flag
                    return 1 + 1;

                case Icode_VAR_INC_DEC:
                case Icode_NAME_INC_DEC:
                case Icode_PROP_INC_DEC:
                case Icode_ELEM_INC_DEC:
                case Icode_REF_INC_DEC:
                    // type of ++/--
                    return 1 + 1;

                case Icode_SHORTNUMBER:
                    // short number
                    return 1 + 2;

                case Icode_INTNUMBER:
                    // int number
                    return 1 + 4;

                case Icode_REG_IND1:
                    // ubyte index
                    return 1 + 1;

                case Icode_REG_IND2:
                    // ushort index
                    return 1 + 2;

                case Icode_REG_IND4:
                    // int index
                    return 1 + 4;

                case Icode_REG_STR1:
                    // ubyte string index
                    return 1 + 1;

                case Icode_REG_STR2:
                    // ushort string index
                    return 1 + 2;

                case Icode_REG_STR4:
                    // int string index
                    return 1 + 4;

                case Icode_GETVAR1:
                case Icode_SETVAR1:
                case Icode_SETCONSTVAR1:
                    // byte var index
                    return 1 + 1;

                case Icode_LINE:
                    // line number
                    return 1 + 2;
            }
            if (!validBytecode(bytecode)) throw Kit.codeBug();
            return 1;
        }
        private static bool validBytecode(int bytecode)
        {
            return validIcode(bytecode) || validTokenCode(bytecode);
        }
        private static bool validIcode(int icode)
        {
            return MIN_ICODE <= icode && icode <= 255;
        }

        private static bool validTokenCode(int token)
        {
            return Token.FIRST_BYTECODE_TOKEN <= token
                   && token <= Token.LAST_BYTECODE_TOKEN;
        }

        private static int getIndex(sbyte[] iCode, int pc)
        {
            return ((iCode[pc] & 0xFF) << 8) | (iCode[pc + 1] & 0xFF);
        }

        /// <summary>
        /// 得到行号
        /// </summary>
        /// <param name="data"></param>
        /// <returns></returns>
        public static int[] getLineNumbers(InterpreterData data)
        {
            UintMap presentLines = new UintMap();

            sbyte[] iCode = data.itsICode;
            int iCodeLength = iCode.Length;
            for (int pc = 0; pc != iCodeLength; )
            {
                int bytecode = iCode[pc];
                int span = bytecodeSpan(bytecode);
                if (bytecode == Icode_LINE)
                {
                    if (span != 3) Kit.codeBug();
                    int line = getIndex(iCode, pc + 1);
                    presentLines.put(line, 0);
                }
                pc += span;
            }

            return presentLines.getKeys();
        }

        private void addToken(int token)
        {
            if (!validTokenCode(token)) throw Kit.codeBug();
            addUint8(token);
        }

        private void addIcode(int icode)
        {
            if (!validIcode(icode)) throw Kit.codeBug();
            // Write negative icode as uint8 bits
            addUint8(icode & 0xFF);
        }

        private sbyte[] increaseICodeCapacity(int extraSize)
        {
            int capacity = itsData.itsICode.Length;
            int top = itsICodeTop;
            if (top + extraSize <= capacity) throw Kit.codeBug();
            capacity *= 2;
            if (top + extraSize > capacity)
            {
                capacity = top + extraSize;
            }
            sbyte[] array = new sbyte[capacity];
            Array.Copy(itsData.itsICode, 0, array, 0, top);
            itsData.itsICode = array;
            return array;
        }

        private void addUint8(int value)
        {
            if ((value & ~0xFF) != 0) throw Kit.codeBug();
            sbyte[] array = itsData.itsICode;
            int top = itsICodeTop;
            if (top == array.Length)
            {
                array = increaseICodeCapacity(1);
            }
            array[top] = (sbyte)value;
            itsICodeTop = top + 1;
        }

        private void addUint16(int value)
        {
            if ((value & ~0xFFFF) != 0) throw Kit.codeBug();
            sbyte[] array = itsData.itsICode;
            int top = itsICodeTop;
            if (top + 2 > array.Length)
            {
                array = increaseICodeCapacity(2);
            }
            array[top] = (sbyte)MathKit.foo(value, 8);
            array[top + 1] = (sbyte)value;
            itsICodeTop = top + 2;
        }

        private void addInt(int i)
        {
            sbyte[] array = itsData.itsICode;
            int top = itsICodeTop;
            if (top + 4 > array.Length)
            {
                array = increaseICodeCapacity(4);
            }
            array[top] = (sbyte)MathKit.foo(i, 24);
            array[top + 1] = (sbyte)MathKit.foo(i, 16);
            array[top + 2] = (sbyte)MathKit.foo(i, 8);
            array[top + 3] = (sbyte)i;
            itsICodeTop = top + 4;
        }

        private void generateNestedFunctions()
        {
            int functionCount = scriptOrFn.getFunctionCount();
            if (functionCount == 0) return;

            InterpreterData[] array = new InterpreterData[functionCount];
            for (int i = 0; i != functionCount; i++)
            {
                FunctionNode def = scriptOrFn.getFunctionNode(i);
                Interpreter jsi = new Interpreter();
                jsi.compilerEnv = compilerEnv;
                jsi.scriptOrFn = def;
                jsi.itsData = new InterpreterData(itsData);
                jsi.generateFunctionICode();
                array[i] = jsi.itsData;
            }
            itsData.itsNestedFunctions = array;
        }
        private void generateRegExpLiterals()
        {
            int N = scriptOrFn.getRegexpCount();
            if (N == 0) return;

            Context cx = Context.getContext();
            RegExpProxy rep = ScriptRuntime.checkRegExpProxy(cx);
            Object[] array = new Object[N];
            for (int i = 0; i != N; i++)
            {
                String string1 = scriptOrFn.getRegexpString(i);
                String flags = scriptOrFn.getRegexpFlags(i);
                array[i] = rep.compileRegExp(cx, string1, flags);
            }
            itsData.itsRegExpLiterals = array;
        }
        /// <summary>
        /// 加入索引在方法调用参数中使用
        /// </summary>
        /// <param name="op"></param>
        /// <param name="index"></param>
        private void addIndexOp(int op, int index)
        {
            addIndexPrefix(index);
            if (validIcode(op))
            {
                addIcode(op);
            }
            else
            {
                addToken(op);
            }
        }

        private void addStringPrefix(String str)
        {
            int index = itsStrings.get(str, -1);
            if (index == -1)
            {
                index = itsStrings.size();
                itsStrings.put(str, index);
            }
            if (index < 4)
            {
                addIcode(Icode_REG_STR_C0 - index);
            }
            else if (index <= 0xFF)
            {
                addIcode(Icode_REG_STR1);
                addUint8(index);
            }
            else if (index <= 0xFFFF)
            {
                addIcode(Icode_REG_STR2);
                addUint16(index);
            }
            else
            {
                addIcode(Icode_REG_STR4);
                addInt(index);
            }
        }

        private void addIndexPrefix(int index)
        {
            if (index < 0) Kit.codeBug();
            if (index < 6)
            {
                addIcode(Icode_REG_IND_C0 - index);
            }
            else if (index <= 0xFF)
            {
                addIcode(Icode_REG_IND1);
                addUint8(index);
            }
            else if (index <= 0xFFFF)
            {
                addIcode(Icode_REG_IND2);
                addUint16(index);
            }
            else
            {
                addIcode(Icode_REG_IND4);
                addInt(index);
            }
        }

        private void addExceptionHandler(int icodeStart, int icodeEnd,
                                         int handlerStart, bool isFinally,
                                         int exceptionObjectLocal, int scopeLocal)
        {
            int top = itsExceptionTableTop;
            int[] table = itsData.itsExceptionTable;
            if (table == null)
            {
                if (top != 0) Kit.codeBug();
                table = new int[EXCEPTION_SLOT_SIZE * 2];
                itsData.itsExceptionTable = table;
            }
            else if (table.Length == top)
            {
                table = new int[table.Length * 2];
                Array.Copy(itsData.itsExceptionTable, 0, table, 0, top);
                itsData.itsExceptionTable = table;
            }
            table[top + EXCEPTION_TRY_START_SLOT] = icodeStart;
            table[top + EXCEPTION_TRY_END_SLOT] = icodeEnd;
            table[top + EXCEPTION_HANDLER_SLOT] = handlerStart;
            table[top + EXCEPTION_TYPE_SLOT] = isFinally ? 1 : 0;
            table[top + EXCEPTION_LOCAL_SLOT] = exceptionObjectLocal;
            table[top + EXCEPTION_SCOPE_SLOT] = scopeLocal;

            itsExceptionTableTop = top + EXCEPTION_SLOT_SIZE;
        }
        /// <summary>
        /// 调整栈
        /// </summary>
        /// <param name="change"></param>
        private void stackChange(int change)
        {
            if (change <= 0)
            {
                itsStackDepth += change;
            }
            else
            {
                int newDepth = itsStackDepth + change;
                if (newDepth > itsData.itsMaxStack)
                {
                    itsData.itsMaxStack = newDepth;
                }
                itsStackDepth = newDepth;
            }
        }

        private int allocLocal()
        {
            int localSlot = itsLocalTop;
            ++itsLocalTop;
            if (itsLocalTop > itsData.itsMaxLocals)
            {
                itsData.itsMaxLocals = itsLocalTop;
            }
            return localSlot;
        }

        private void releaseLocal(int localSlot)
        {
            --itsLocalTop;
            if (localSlot != itsLocalTop) Kit.codeBug();
        }
        private void updateLineNumber(Node node)
        {
            int lineno = node.getLineno();
            if (lineno != itsLineNumber && lineno >= 0)
            {
                if (itsData.firstLinePC < 0)
                {
                    itsData.firstLinePC = lineno;
                }
                itsLineNumber = lineno;
                addIcode(Icode_LINE);
                addUint16(lineno & 0xFFFF);
            }
        }


        private int getDoubleIndex(double num)
        {
            int index = itsDoubleTableTop;
            if (index == 0)
            {
                itsData.itsDoubleTable = new double[64];
            }
            else if (itsData.itsDoubleTable.Length == index)
            {
                double[] na = new double[index * 2];
                Array.Copy(itsData.itsDoubleTable, 0, na, 0, index);
                itsData.itsDoubleTable = na;
            }
            itsData.itsDoubleTable[index] = num;
            itsDoubleTableTop = index + 1;
            return index;
        }

        private void addGotoOp(int gotoOp)
        {
            sbyte[] array = itsData.itsICode;
            int top = itsICodeTop;
            if (top + 3 > array.Length)
            {
                array = increaseICodeCapacity(3);
            }
            array[top] = (sbyte)gotoOp;
            // Offset would written later
            itsICodeTop = top + 1 + 2;
        }

        private void addVarOp(int op, int varIndex)
        {
            switch (op)
            {
                // fallthrough
                case Icode_VAR_INC_DEC:
                addV:
                    {
                        addIndexOp(op, varIndex);
                        return;
                    }
                case Token.SETCONSTVAR:
                if (varIndex < 128)
                {
                    addIcode(Icode_SETCONSTVAR1);
                    addUint8(varIndex);
                    return;
                }
                addIndexOp(Icode_SETCONSTVAR, varIndex);
                return;
                case Token.GETVAR:
                case Token.SETVAR:
                {
                    if (varIndex < 128)
                    {
                        addIcode(op == Token.GETVAR ? Icode_GETVAR1 : Icode_SETVAR1);
                        addUint8(varIndex);
                        return;
                    }
                    goto addV;
                }

            }
            throw Kit.codeBug();
        }

        private void addStringOp(int op, String str)
        {
            addStringPrefix(str);
            if (validIcode(op))
            {
                addIcode(op);
            }
            else
            {
                addToken(op);
            }
        }

        private int getLocalBlockRef(Node node)
        {
            Node localBlock = (Node)node.getProp(Node.LOCAL_BLOCK_PROP);
            return localBlock.getExistingIntProp(Node.LOCAL_PROP);
        }
        private void generateCallFunAndThis(Node left)
        {
            // Generate code to place on stack function and thisObj
            int type = left.getType();
            switch (type)
            {
                case Token.NAME:
                    {
                        String name = left.getString();
                        // 栈: ... -> ... function thisObj
                        addStringOp(Icode_NAME_AND_THIS, name);
                        stackChange(2);
                        break;
                    }
                case Token.GETPROP:
                case Token.GETELEM:
                    {
                        Node target = left.getFirstChild();
                        visitExpression(target, 0);
                        Node id = target.getNext();
                        if (type == Token.GETPROP)
                        {
                            String property = id.getString();
                            // 栈: ... target -> ... function thisObj
                            addStringOp(Icode_PROP_AND_THIS, property);
                            stackChange(1);
                        }
                        else
                        {
                            visitExpression(id, 0);
                            // 栈: ... target id -> ... function thisObj
                            addIcode(Icode_ELEM_AND_THIS);
                        }
                        break;
                    }
                default:
                    // 包含 Token.GETVAR
                    visitExpression(left, 0);
                    // 栈: ... value -> ... function thisObj
                    addIcode(Icode_VALUE_AND_THIS);
                    stackChange(1);
                    break;
            }
        }

        private void resolveForwardGoto(int fromPC)
        {
            // Ensure that forward jump skips at least self bytecode
            if (itsICodeTop < fromPC + 3) throw Kit.codeBug();
            resolveGoto(fromPC, itsICodeTop);
        }

        private void visitIncDec(Node node, Node child)
        {
            int incrDecrMask = node.getExistingIntProp(Node.INCRDECR_PROP);
            int childType = child.getType();
            switch (childType)
            {
                case Token.GETVAR:
                    {
                        if (itsData.itsNeedsActivation) Kit.codeBug();
                        int i = scriptOrFn.getIndexForNameNode(child);
                        addVarOp(Icode_VAR_INC_DEC, i);
                        addUint8(incrDecrMask);
                        stackChange(1);
                        break;
                    }
                case Token.NAME:
                    {
                        String name = child.getString();
                        addStringOp(Icode_NAME_INC_DEC, name);
                        addUint8(incrDecrMask);
                        stackChange(1);
                        break;
                    }
                case Token.GETPROP:
                    {
                        Node object1 = child.getFirstChild();
                        visitExpression(object1, 0);
                        String property = object1.getNext().getString();
                        addStringOp(Icode_PROP_INC_DEC, property);
                        addUint8(incrDecrMask);
                        break;
                    }
                case Token.GETELEM:
                    {
                        Node object1 = child.getFirstChild();
                        visitExpression(object1, 0);
                        Node index = object1.getNext();
                        visitExpression(index, 0);
                        addIcode(Icode_ELEM_INC_DEC);
                        addUint8(incrDecrMask);
                        stackChange(-1);
                        break;
                    }
                case Token.GET_REF:
                    {
                        Node ref1 = child.getFirstChild();
                        visitExpression(ref1, 0);
                        addIcode(Icode_REF_INC_DEC);
                        addUint8(incrDecrMask);
                        break;
                    }
                default:
                    {
                        throw badTree(node);
                    }
            }
        }

        private void visitLiteral(Node node, Node child)
        {
            int type = node.getType();
            int count;
            Object[] propertyIds = null;
            if (type == Token.ARRAYLIT)
            {
                count = 0;
                for (Node n = child; n != null; n = n.getNext())
                {
                    ++count;
                }
            }
            else if (type == Token.OBJECTLIT)
            {
                propertyIds = (Object[])node.getProp(Node.OBJECT_IDS_PROP);
                count = propertyIds.Length;
            }
            else
            {
                throw badTree(node);
            }
            addIndexOp(Icode_LITERAL_NEW, count);
            stackChange(2);
            while (child != null)
            {
                int childType = child.getType();
                if (childType == Token.GET)
                {
                    visitExpression(child.getFirstChild(), 0);
                    addIcode(Icode_LITERAL_GETTER);
                }
                else if (childType == Token.SET)
                {
                    visitExpression(child.getFirstChild(), 0);
                    addIcode(Icode_LITERAL_SETTER);
                }
                else
                {
                    visitExpression(child, 0);
                    addIcode(Icode_LITERAL_SET);
                }
                stackChange(-1);
                child = child.getNext();
            }
            if (type == Token.ARRAYLIT)
            {
                int[] skipIndexes = (int[])node.getProp(Node.SKIP_INDEXES_PROP);
                if (skipIndexes == null)
                {
                    addToken(Token.ARRAYLIT);
                }
                else
                {
                    int index = itsLiteralIds.size();
                    itsLiteralIds.add(skipIndexes);
                    addIndexOp(Icode_SPARE_ARRAYLIT, index);
                }
            }
            else
            {
                int index = itsLiteralIds.size();
                itsLiteralIds.add(propertyIds);
                addIndexOp(Token.OBJECTLIT, index);
            }
            stackChange(-1);
        }

        private void visitArrayComprehension(Node node, Node initStmt, Node expr)
        {
            // A bit of a hack: array comprehensions are implemented using
            // statement nodes for the iteration, yet they appear in an
            // expression context. So we pass the current stack depth to
            // visitStatement so it can check that the depth is not altered
            // by statements.
            visitStatement(initStmt, itsStackDepth);
            visitExpression(expr, 0);
        }

        private void visitExpression(Node node, int contextFlags)
        {
            int type = node.getType();
            Node child = node.getFirstChild();
            int savedStackDepth = itsStackDepth;
            switch (type)
            {

                case Token.FUNCTION:
                    {
                        int fnIndex = node.getExistingIntProp(Node.FUNCTION_PROP);
                        FunctionNode fn = scriptOrFn.getFunctionNode(fnIndex);
                        // See comments in visitStatement for Token.FUNCTION case
                        if (fn.getFunctionType() != FunctionNode.FUNCTION_EXPRESSION)
                        {
                            throw Kit.codeBug();
                        }
                        addIndexOp(Icode_CLOSURE_EXPR, fnIndex);
                        stackChange(1);
                    }
                    break;

                case Token.LOCAL_LOAD:
                    {
                        int localIndex = getLocalBlockRef(node);
                        addIndexOp(Token.LOCAL_LOAD, localIndex);
                        stackChange(1);
                    }
                    break;

                case Token.COMMA:
                    {
                        Node lastChild = node.getLastChild();
                        while (child != lastChild)
                        {
                            visitExpression(child, 0);
                            addIcode(Icode_POP);
                            stackChange(-1);
                            child = child.getNext();
                        }
                        // Preserve tail context flag if any
                        visitExpression(child, contextFlags & ECF_TAIL);
                    }
                    break;

                case Token.USE_STACK:
                    // Indicates that stack was modified externally,
                    // like placed catch object
                    stackChange(1);
                    break;

                case Token.REF_CALL:
                case Token.CALL:
                case Token.NEW:
                    {
                        if (type == Token.NEW)
                        {
                            visitExpression(child, 0);
                        }
                        else
                        {
                            generateCallFunAndThis(child);
                        }
                        int argCount = 0;
                        while ((child = child.getNext()) != null)
                        {
                            visitExpression(child, 0);
                            ++argCount;
                        }
                        int callType = node.getIntProp(Node.SPECIALCALL_PROP,
                                                       Node.NON_SPECIALCALL);
                        if (callType != Node.NON_SPECIALCALL)
                        {
                            // embed line number and source filename
                            addIndexOp(Icode_CALLSPECIAL, argCount);
                            addUint8(callType);
                            addUint8(type == Token.NEW ? 1 : 0);
                            addUint16(itsLineNumber & 0xFFFF);
                        }
                        else
                        {
                            // Only use the tail call optimization if we're not in a try
                            // or we're not generating debug info (since the
                            // optimization will confuse the debugger)
                            if (type == Token.CALL && (contextFlags & ECF_TAIL) != 0 &&
                                !compilerEnv.isGenerateDebugInfo() && !itsInTryFlag)
                            {
                                type = Icode_TAIL_CALL;
                            }
                            addIndexOp(type, argCount);
                        }

                        if (type == Token.NEW)
                        {
                            // new: f, args -> result
                            stackChange(-argCount);
                        }
                        else
                        {
                            // call: f, thisObj, args -> result　调用
                            // ref_call: f, thisObj, args -> ref 引用
                            stackChange(-1 - argCount);
                        }
                        if (argCount > itsData.itsMaxCalleeArgs)
                        {
                            itsData.itsMaxCalleeArgs = argCount;
                        }
                    }
                    break;

                case Token.AND:
                case Token.OR:
                    {
                        visitExpression(child, 0);
                        addIcode(Icode_DUP);
                        stackChange(1);
                        int afterSecondJumpStart = itsICodeTop;
                        int jump = (type == Token.AND) ? Token.IFNE : Token.IFEQ;
                        addGotoOp(jump);
                        stackChange(-1);
                        addIcode(Icode_POP);
                        stackChange(-1);
                        child = child.getNext();
                        // Preserve tail context flag if any
                        visitExpression(child, contextFlags & ECF_TAIL);
                        resolveForwardGoto(afterSecondJumpStart);
                    }
                    break;

                case Token.HOOK:
                    {
                        Node ifThen = child.getNext();
                        Node ifElse = ifThen.getNext();
                        visitExpression(child, 0);
                        int elseJumpStart = itsICodeTop;
                        addGotoOp(Token.IFNE);
                        stackChange(-1);
                        // Preserve tail context flag if any
                        visitExpression(ifThen, contextFlags & ECF_TAIL);
                        int afterElseJumpStart = itsICodeTop;
                        addGotoOp(Token.GOTO);
                        resolveForwardGoto(elseJumpStart);
                        itsStackDepth = savedStackDepth;
                        // Preserve tail context flag if any
                        visitExpression(ifElse, contextFlags & ECF_TAIL);
                        resolveForwardGoto(afterElseJumpStart);
                    }
                    break;

                case Token.GETPROP:
                case Token.GETPROPNOWARN:
                    visitExpression(child, 0);
                    child = child.getNext();
                    addStringOp(type, child.getString());
                    break;

                case Token.GETELEM:
                case Token.DELPROP:
                case Token.BITAND:
                case Token.BITOR:
                case Token.BITXOR:
                case Token.LSH:
                case Token.RSH:
                case Token.URSH:
                case Token.ADD:
                case Token.SUB:
                case Token.MOD:
                case Token.DIV:
                case Token.MUL:
                case Token.EQ:
                case Token.NE:
                case Token.SHEQ:
                case Token.SHNE:
                case Token.IN:
                case Token.INSTANCEOF:
                case Token.LE:
                case Token.LT:
                case Token.GE:
                case Token.GT:
                    visitExpression(child, 0);
                    child = child.getNext();
                    visitExpression(child, 0);
                    addToken(type);
                    stackChange(-1);
                    break;

                case Token.POS:
                case Token.NEG:
                case Token.NOT:
                case Token.BITNOT:
                case Token.TYPEOF:
                case Token.VOID:
                    visitExpression(child, 0);
                    if (type == Token.VOID)
                    {
                        addIcode(Icode_POP);
                        addIcode(Icode_UNDEF);
                    }
                    else
                    {
                        addToken(type);
                    }
                    break;

                case Token.GET_REF:
                case Token.DEL_REF:
                    visitExpression(child, 0);
                    addToken(type);
                    break;

                case Token.SETPROP:
                case Token.SETPROP_OP:
                    {
                        visitExpression(child, 0);
                        child = child.getNext();
                        String property = child.getString();
                        child = child.getNext();
                        if (type == Token.SETPROP_OP)
                        {
                            addIcode(Icode_DUP);
                            stackChange(1);
                            addStringOp(Token.GETPROP, property);
                            // Compensate for the following USE_STACK
                            stackChange(-1);
                        }
                        visitExpression(child, 0);
                        addStringOp(Token.SETPROP, property);
                        stackChange(-1);
                    }
                    break;

                case Token.SETELEM:
                case Token.SETELEM_OP:
                    visitExpression(child, 0);
                    child = child.getNext();
                    visitExpression(child, 0);
                    child = child.getNext();
                    if (type == Token.SETELEM_OP)
                    {
                        addIcode(Icode_DUP2);
                        stackChange(2);
                        addToken(Token.GETELEM);
                        stackChange(-1);
                        // Compensate for the following USE_STACK
                        stackChange(-1);
                    }
                    visitExpression(child, 0);
                    addToken(Token.SETELEM);
                    stackChange(-2);
                    break;

                case Token.SET_REF:
                case Token.SET_REF_OP:
                    visitExpression(child, 0);
                    child = child.getNext();
                    if (type == Token.SET_REF_OP)
                    {
                        addIcode(Icode_DUP);
                        stackChange(1);
                        addToken(Token.GET_REF);
                        // Compensate for the following USE_STACK
                        stackChange(-1);
                    }
                    visitExpression(child, 0);
                    addToken(Token.SET_REF);
                    stackChange(-1);
                    break;

                case Token.SETNAME:
                    {
                        String name = child.getString();
                        visitExpression(child, 0);
                        child = child.getNext();
                        visitExpression(child, 0);
                        addStringOp(Token.SETNAME, name);
                        stackChange(-1);
                    }
                    break;

                case Token.SETCONST:
                    {
                        String name = child.getString();
                        visitExpression(child, 0);
                        child = child.getNext();
                        visitExpression(child, 0);
                        addStringOp(Icode_SETCONST, name);
                        stackChange(-1);
                    }
                    break;

                case Token.TYPEOFNAME:
                    {
                        int index = -1;
                        // use typeofname if an activation frame exists
                        // since the vars all exist there instead of in jregs
                        if (itsInFunctionFlag && !itsData.itsNeedsActivation)
                            index = scriptOrFn.getIndexForNameNode(node);
                        if (index == -1)
                        {
                            addStringOp(Icode_TYPEOFNAME, node.getString());
                            stackChange(1);
                        }
                        else
                        {
                            addVarOp(Token.GETVAR, index);
                            stackChange(1);
                            addToken(Token.TYPEOF);
                        }
                    }
                    break;

                case Token.BINDNAME:
                case Token.NAME:
                case Token.STRING:
                    addStringOp(type, node.getString());
                    stackChange(1);
                    break;

                case Token.INC:
                case Token.DEC:
                    visitIncDec(node, child);
                    break;

                case Token.NUMBER:
                    {
                        double num = node.getDouble();
                        int inum = (int)num;
                        if (inum == num)
                        {
                            if (inum == 0)
                            {
                                addIcode(Icode_ZERO);
                                // Check for negative zero
                                if (1.0 / num < 0.0)
                                {
                                    addToken(Token.NEG);
                                }
                            }
                            else if (inum == 1)
                            {
                                addIcode(Icode_ONE);
                            }
                            else if ((short)inum == inum)
                            {
                                addIcode(Icode_SHORTNUMBER);
                                // write short as uin16 bit pattern
                                addUint16(inum & 0xFFFF);
                            }
                            else
                            {
                                addIcode(Icode_INTNUMBER);
                                addInt(inum);
                            }
                        }
                        else
                        {
                            int index = getDoubleIndex(num);
                            addIndexOp(Token.NUMBER, index);
                        }
                        stackChange(1);
                    }
                    break;

                case Token.GETVAR:
                    {
                        if (itsData.itsNeedsActivation) Kit.codeBug();
                        int index = scriptOrFn.getIndexForNameNode(node);
                        addVarOp(Token.GETVAR, index);
                        stackChange(1);
                    }
                    break;

                case Token.SETVAR:
                    {
                        if (itsData.itsNeedsActivation) Kit.codeBug();
                        int index = scriptOrFn.getIndexForNameNode(child);
                        child = child.getNext();
                        visitExpression(child, 0);
                        addVarOp(Token.SETVAR, index);
                    }
                    break;

                case Token.SETCONSTVAR:
                    {
                        if (itsData.itsNeedsActivation) Kit.codeBug();
                        int index = scriptOrFn.getIndexForNameNode(child);
                        child = child.getNext();
                        visitExpression(child, 0);
                        addVarOp(Token.SETCONSTVAR, index);
                    }
                    break;

                case Token.NULL:
                case Token.THIS:
                case Token.THISFN:
                case Token.FALSE:
                case Token.TRUE:
                case Token.UNDEFINED:
                    addToken(type);
                    stackChange(1);
                    break;

                case Token.ENUM_NEXT:
                case Token.ENUM_ID:
                    addIndexOp(type, getLocalBlockRef(node));
                    stackChange(1);
                    break;

                case Token.REGEXP:
                    {
                        int index = node.getExistingIntProp(Node.REGEXP_PROP);
                        addIndexOp(Token.REGEXP, index);
                        stackChange(1);
                    }
                    break;

                case Token.ARRAYLIT:
                case Token.OBJECTLIT:
                    visitLiteral(node, child);
                    break;

                case Token.ARRAYCOMP:
                    visitArrayComprehension(node, child, child.getNext());
                    break;

                case Token.REF_SPECIAL:
                    visitExpression(child, 0);
                    addStringOp(type, (String)node.getProp(Node.NAME_PROP));
                    break;

                case Token.REF_MEMBER:
                case Token.REF_NS_MEMBER:
                case Token.REF_NAME:
                case Token.REF_NS_NAME:
                    {
                        int memberTypeFlags = node.getIntProp(Node.MEMBER_TYPE_PROP, 0);
                        // generate possible target, possible namespace and member
                        int childCount = 0;
                        do
                        {
                            visitExpression(child, 0);
                            ++childCount;
                            child = child.getNext();
                        } while (child != null);
                        addIndexOp(type, memberTypeFlags);
                        stackChange(1 - childCount);
                    }
                    break;

                case Token.DOTQUERY:
                    {
                        int queryPC;
                        updateLineNumber(node);
                        visitExpression(child, 0);
                        addIcode(Icode_ENTERDQ);
                        stackChange(-1);
                        queryPC = itsICodeTop;
                        visitExpression(child.getNext(), 0);
                        addBackwardGoto(Icode_LEAVEDQ, queryPC);
                    }
                    break;

                case Token.DEFAULTNAMESPACE:
                case Token.ESCXMLATTR:
                case Token.ESCXMLTEXT:
                    visitExpression(child, 0);
                    addToken(type);
                    break;

                case Token.YIELD:
                    if (child != null)
                    {
                        visitExpression(child, 0);
                    }
                    else
                    {
                        addIcode(Icode_UNDEF);
                        stackChange(1);
                    }
                    addToken(Token.YIELD);
                    addUint16(node.getLineno() & 0xFFFF);
                    break;

                case Token.WITHEXPR:
                    {
                        Node enterWith = node.getFirstChild();
                        Node with = enterWith.getNext();
                        visitExpression(enterWith.getFirstChild(), 0);
                        addToken(Token.ENTERWITH);
                        stackChange(-1);
                        visitExpression(with.getFirstChild(), 0);
                        addToken(Token.LEAVEWITH);
                        break;
                    }

                default:
                    throw badTree(node);
            }
            if (savedStackDepth + 1 != itsStackDepth)
            {
                Kit.codeBug();
            }
        }
        private void addBackwardGoto(int gotoOp, int jumpPC)
        {
            int fromPC = itsICodeTop;
            // Ensure that this is a jump backward
            if (fromPC <= jumpPC) throw Kit.codeBug();
            addGotoOp(gotoOp);
            resolveGoto(fromPC, jumpPC);
        }

        private Exception badTree(Node node)
        {
            throw new Exception(node.ToString());
        }
        private void markTargetLabel(Node target)
        {
            int label = getTargetLabel(target);
            if (itsLabelTable[label] != -1)
            {
                // Can mark label only once
                Kit.codeBug();
            }
            itsLabelTable[label] = itsICodeTop;
        }
        private void visitStatement(Node node, int initialStackDepth)
        {
            int type = node.getType();
            Node child = node.getFirstChild();
            switch (type)
            {

                case Token.FUNCTION:
                    {
                        int fnIndex = node.getExistingIntProp(Node.FUNCTION_PROP);
                        int fnType = scriptOrFn.getFunctionNode(fnIndex).
                                         getFunctionType();
                        // Only function expressions or function expression
                        // statements need closure code creating new function
                        // object on stack as function statements are initialized
                        // at script/function start.
                        // In addition, function expressions can not be present here
                        // at statement level, they must only be present as expressions.
                        if (fnType == FunctionNode.FUNCTION_EXPRESSION_STATEMENT)
                        {
                            addIndexOp(Icode_CLOSURE_STMT, fnIndex);
                        }
                        else
                        {
                            if (fnType != FunctionNode.FUNCTION_STATEMENT)
                            {
                                throw Kit.codeBug();
                            }
                        }
                        // For function statements or function expression statements
                        // in scripts, we need to ensure that the result of the script
                        // is the function if it is the last statement in the script.
                        // For example, eval("function () {}") should return a
                        // function, not undefined.
                        if (!itsInFunctionFlag)
                        {
                            addIndexOp(Icode_CLOSURE_EXPR, fnIndex);
                            stackChange(1);
                            addIcode(Icode_POP_RESULT);
                            stackChange(-1);
                        }
                    }
                    break;
                case Token.SCRIPT:
                scr:
                    {
                        // fall through
                        while (child != null)
                        {
                            visitStatement(child, initialStackDepth);
                            child = child.getNext();
                        }
                        break;
                    }
                case Token.LABEL:
                case Token.LOOP:
                case Token.BLOCK:
                case Token.EMPTY:
                case Token.WITH:
                {
                    updateLineNumber(node);
                    goto scr;
                }
                case Token.ENTERWITH:
                visitExpression(child, 0);
                addToken(Token.ENTERWITH);
                stackChange(-1);
                break;

                case Token.LEAVEWITH:
                addToken(Token.LEAVEWITH);
                break;

                case Token.LOCAL_BLOCK:
                {
                    int local = allocLocal();
                    node.putIntProp(Node.LOCAL_PROP, local);
                    updateLineNumber(node);
                    while (child != null)
                    {
                        visitStatement(child, initialStackDepth);
                        child = child.getNext();
                    }
                    addIndexOp(Icode_LOCAL_CLEAR, local);
                    releaseLocal(local);
                }
                break;

                case Token.DEBUGGER:
                addIcode(Icode_DEBUGGER);
                break;

                case Token.SWITCH:
                updateLineNumber(node);
                // See comments in IRFactory.createSwitch() for description
                // of SWITCH node
                {
                    visitExpression(child, 0);
                    for (Node.Jump caseNode = (Node.Jump)child.getNext();
                         caseNode != null;
                         caseNode = (Node.Jump)caseNode.getNext())
                    {
                        if (caseNode.getType() != Token.CASE)
                            throw badTree(caseNode);
                        Node test = caseNode.getFirstChild();
                        addIcode(Icode_DUP);
                        stackChange(1);
                        visitExpression(test, 0);
                        addToken(Token.SHEQ);
                        stackChange(-1);
                        // If true, Icode_IFEQ_POP will jump and remove case
                        // value from stack
                        addGoto(caseNode.target, Icode_IFEQ_POP);
                        stackChange(-1);
                    }
                    addIcode(Icode_POP);
                    stackChange(-1);
                }
                break;

                case Token.TARGET:
                markTargetLabel(node);
                break;

                case Token.IFEQ:
                case Token.IFNE:
                {
                    Node target = ((Node.Jump)node).target;
                    visitExpression(child, 0);
                    addGoto(target, type);
                    stackChange(-1);
                }
                break;

                case Token.GOTO:
                {
                    Node target = ((Node.Jump)node).target;
                    addGoto(target, type);
                }
                break;

                case Token.JSR:
                {
                    Node target = ((Node.Jump)node).target;
                    addGoto(target, Icode_GOSUB);
                }
                break;

                case Token.FINALLY:
                {
                    // Account for incomming GOTOSUB address
                    stackChange(1);
                    int finallyRegister = getLocalBlockRef(node);
                    addIndexOp(Icode_STARTSUB, finallyRegister);
                    stackChange(-1);
                    while (child != null)
                    {
                        visitStatement(child, initialStackDepth);
                        child = child.getNext();
                    }
                    addIndexOp(Icode_RETSUB, finallyRegister);
                }
                break;

                case Token.EXPR_VOID:
                case Token.EXPR_RESULT:
                updateLineNumber(node);
                visitExpression(child, 0);
                addIcode((type == Token.EXPR_VOID) ? Icode_POP : Icode_POP_RESULT);
                stackChange(-1);
                break;

                case Token.TRY:
                {
                    Node.Jump tryNode = (Node.Jump)node;
                    int exceptionObjectLocal = getLocalBlockRef(tryNode);
                    int scopeLocal = allocLocal();

                    addIndexOp(Icode_SCOPE_SAVE, scopeLocal);

                    int tryStart = itsICodeTop;
                    bool savedFlag = itsInTryFlag;
                    itsInTryFlag = true;
                    while (child != null)
                    {
                        visitStatement(child, initialStackDepth);
                        child = child.getNext();
                    }
                    itsInTryFlag = savedFlag;

                    Node catchTarget = tryNode.target;
                    if (catchTarget != null)
                    {
                        int catchStartPC
                            = itsLabelTable[getTargetLabel(catchTarget)];
                        addExceptionHandler(
                            tryStart, catchStartPC, catchStartPC,
                            false, exceptionObjectLocal, scopeLocal);
                    }
                    Node finallyTarget = tryNode.getFinally();
                    if (finallyTarget != null)
                    {
                        int finallyStartPC
                            = itsLabelTable[getTargetLabel(finallyTarget)];
                        addExceptionHandler(
                            tryStart, finallyStartPC, finallyStartPC,
                            true, exceptionObjectLocal, scopeLocal);
                    }

                    addIndexOp(Icode_LOCAL_CLEAR, scopeLocal);
                    releaseLocal(scopeLocal);
                }
                break;

                case Token.CATCH_SCOPE:
                {
                    int localIndex = getLocalBlockRef(node);
                    int scopeIndex = node.getExistingIntProp(Node.CATCH_SCOPE_PROP);
                    String name = child.getString();
                    child = child.getNext();
                    visitExpression(child, 0); // load expression object
                    addStringPrefix(name);
                    addIndexPrefix(localIndex);
                    addToken(Token.CATCH_SCOPE);
                    addUint8(scopeIndex != 0 ? 1 : 0);
                    stackChange(-1);
                }
                break;

                case Token.THROW:
                updateLineNumber(node);
                visitExpression(child, 0);
                addToken(Token.THROW);
                addUint16(itsLineNumber & 0xFFFF);
                stackChange(-1);
                break;

                case Token.RETHROW:
                updateLineNumber(node);
                addIndexOp(Token.RETHROW, getLocalBlockRef(node));
                break;

                case Token.RETURN:
                updateLineNumber(node);
                if (node.getIntProp(Node.GENERATOR_END_PROP, 0) != 0)
                {
                    // We're in a generator, so change RETURN to GENERATOR_END
                    addIcode(Icode_GENERATOR_END);
                    addUint16(itsLineNumber & 0xFFFF);
                }
                else if (child != null)
                {
                    visitExpression(child, ECF_TAIL);
                    addToken(Token.RETURN);
                    stackChange(-1);
                }
                else
                {
                    addIcode(Icode_RETUNDEF);
                }
                break;

                case Token.RETURN_RESULT:
                updateLineNumber(node);
                addToken(Token.RETURN_RESULT);
                break;

                case Token.ENUM_INIT_KEYS:
                case Token.ENUM_INIT_VALUES:
                case Token.ENUM_INIT_ARRAY:
                visitExpression(child, 0);
                addIndexOp(type, getLocalBlockRef(node));
                stackChange(-1);
                break;

                case Icode_GENERATOR:
                break;

                default:
                throw badTree(node);
            }

            if (itsStackDepth != initialStackDepth)
            {
                throw Kit.codeBug();
            }
        }

        private int getTargetLabel(Node target)
        {
            int label = target.labelId();
            if (label != -1)
            {
                return label;
            }
            label = itsLabelTableTop;
            if (itsLabelTable == null || label == itsLabelTable.Length)
            {
                if (itsLabelTable == null)
                {
                    itsLabelTable = new int[MIN_LABEL_TABLE_SIZE];
                }
                else
                {
                    int[] tmp = new int[itsLabelTable.Length * 2];
                    Array.Copy(itsLabelTable, 0, tmp, 0, label);
                    itsLabelTable = tmp;
                }
            }
            itsLabelTableTop = label + 1;
            itsLabelTable[label] = -1;

            target.labelId(label);
            return label;
        }
        private void addGoto(Node target, int gotoOp)
        {
            int label = getTargetLabel(target);
            if (!(label < itsLabelTableTop)) Kit.codeBug();
            int targetPC = itsLabelTable[label];

            if (targetPC != -1)
            {
                addBackwardGoto(gotoOp, targetPC);
            }
            else
            {
                int gotoPC = itsICodeTop;
                addGotoOp(gotoOp);
                int top = itsFixupTableTop;
                if (itsFixupTable == null || top == itsFixupTable.Length)
                {
                    if (itsFixupTable == null)
                    {
                        itsFixupTable = new long[MIN_FIXUP_TABLE_SIZE];
                    }
                    else
                    {
                        long[] tmp = new long[itsFixupTable.Length * 2];
                        Array.Copy(itsFixupTable, 0, tmp, 0, top);
                        itsFixupTable = tmp;
                    }
                }
                itsFixupTableTop = top + 1;
                itsFixupTable[top] = ((long)label << 32) | gotoPC;
            }
        }

        public static Object restartContinuation(NativeContinuation c, Context cx,
                                             Scriptable scope, Object[] args)
        {
            if (!ScriptRuntime.hasTopCall(cx))
            {
                return ScriptRuntime.doTopCall(c, cx, scope, null, args);
            }

            Object arg;
            if (args.Length == 0)
            {
                arg = Undefined.instance;
            }
            else
            {
                arg = args[0];
            }

            CallFrame capturedFrame = (CallFrame)c.getImplementation();
            if (capturedFrame == null)
            {
                // No frames to restart
                return arg;
            }

            ContinuationJump cjump = new ContinuationJump(c, null);

            cjump.result = arg;
            return interpretLoop(cx, null, cjump);
        }


        private void resolveGoto(int fromPC, int jumpPC)
        {
            int offset = jumpPC - fromPC;
            // Ensure that jumps do not overlap
            if (0 <= offset && offset <= 2) throw Kit.codeBug();
            int offsetSite = fromPC + 1;
            if (offset != (short)offset)
            {
                if (itsData.longJumps == null)
                {
                    itsData.longJumps = new UintMap();
                }
                itsData.longJumps.put(offsetSite, jumpPC);
                offset = 0;
            }
            sbyte[] array = itsData.itsICode;
            array[offsetSite] = (sbyte)(offset >> 8);
            array[offsetSite + 1] = (sbyte)offset;
        }
        private static int getShort(sbyte[] iCode, int pc)
        {
            int a = ((iCode[pc] << 8) | (iCode[pc + 1] & 0xFF));
            return a;
        }
        private static int getInt(sbyte[] iCode, int pc)
        {
            return ((iCode[pc] << 24) | ((iCode[pc + 1] & 0xFF) << 16)
                   | ((iCode[pc + 2] & 0xFF) << 8) | (iCode[pc + 3] & 0xFF));
        }

        private void fixLabelGotos()
        {
            for (int i = 0; i < itsFixupTableTop; i++)
            {
                long fixup = itsFixupTable[i];
                int label = (int)(fixup >> 32);
                int jumpSource = (int)fixup;
                int pc = itsLabelTable[label];
                if (pc == -1)
                {
                    // Unlocated label
                    throw Kit.codeBug();
                }
                resolveGoto(jumpSource, pc);
            }
            itsFixupTableTop = 0;
        }
        private void generateICodeFromTree(Node tree)
        {
            generateNestedFunctions();

            generateRegExpLiterals();

            visitStatement(tree, 0);
            fixLabelGotos();
            // 加入 RETURN_RESULT 仅当 scripts 做为 function 总是 RETURN　结尾
            if (itsData.itsFunctionType == 0)
            {
                addToken(Token.RETURN_RESULT);
            }

            if (itsData.itsICode.Length != itsICodeTop)
            {
                // Make itsData.itsICode length exactly itsICodeTop to save memory
                // and catch bugs with jumps beyond icode as early as possible
                sbyte[] tmp = new sbyte[itsICodeTop];
                Array.Copy(itsData.itsICode, 0, tmp, 0, itsICodeTop);
                itsData.itsICode = tmp;
            }
            if (itsStrings.size() == 0)
            {
                itsData.itsStringTable = null;
            }
            else
            {
                itsData.itsStringTable = new String[itsStrings.size()];
                ObjToIntMap.Iterator iter = itsStrings.newIterator();
                for (iter.start(); !iter.done(); iter.next())
                {
                    String str = (String)iter.getKey();
                    int index = iter.getValue();
                    if (itsData.itsStringTable[index] != null) Kit.codeBug();
                    itsData.itsStringTable[index] = str;
                }
            }
            if (itsDoubleTableTop == 0)
            {
                itsData.itsDoubleTable = null;
            }
            else if (itsData.itsDoubleTable.Length != itsDoubleTableTop)
            {
                double[] tmp = new double[itsDoubleTableTop];
                Array.Copy(itsData.itsDoubleTable, 0, tmp, 0,
                                 itsDoubleTableTop);
                itsData.itsDoubleTable = tmp;
            }
            if (itsExceptionTableTop != 0
                && itsData.itsExceptionTable.Length != itsExceptionTableTop)
            {
                int[] tmp = new int[itsExceptionTableTop];
                Array.Copy(itsData.itsExceptionTable, 0, tmp, 0,
                                 itsExceptionTableTop);
                itsData.itsExceptionTable = tmp;
            }

            itsData.itsMaxVars = scriptOrFn.getParamAndVarCount();
            // itsMaxFrameArray: interpret method needs this amount for its
            // stack and sDbl arrays
            itsData.itsMaxFrameArray = itsData.itsMaxVars
                                       + itsData.itsMaxLocals
                                       + itsData.itsMaxStack;

            itsData.argNames = scriptOrFn.getParamAndVarNames();
            itsData.argIsConst = scriptOrFn.getParamAndVarConst();
            itsData.argCount = scriptOrFn.getParamCount();

            itsData.encodedSourceStart = scriptOrFn.getEncodedSourceStart();
            itsData.encodedSourceEnd = scriptOrFn.getEncodedSourceEnd();

            if (itsLiteralIds.size() != 0)
            {
                itsData.literalIds = itsLiteralIds.toArray();
            }

            if (Token.printICode) dumpICode(itsData);
        }

        private static void dumpICode(InterpreterData idata)
        {
            if (!Token.printICode)
            {
                return;
            }

            sbyte[] iCode = idata.itsICode;
            int iCodeLength = iCode.Length;
            String[] strings = idata.itsStringTable;
            // PrintStream out = System.out;
            Console.WriteLine("ICode dump, for " + idata.itsName
                        + ", length = " + iCodeLength);
            Console.WriteLine("MaxStack = " + idata.itsMaxStack);

            int indexReg = 0;
            for (int pc = 0; pc < iCodeLength; )
            {
                // out.flush();
                Console.Write(" [" + pc + "] ");
                int token = iCode[pc];
                int icodeLength = bytecodeSpan(token);
                String tname = bytecodeName(token);
                int old_pc = pc;
                ++pc;
                switch (token)
                {
                    default:
                        if (icodeLength != 1) Kit.codeBug();
                        Console.WriteLine(tname);
                        break;

                    case Icode_GOSUB:
                    case Token.GOTO:
                    case Token.IFEQ:
                    case Token.IFNE:
                    case Icode_IFEQ_POP:
                    case Icode_LEAVEDQ:
                        {
                            int newPC = pc + getShort(iCode, pc) - 1;
                            Console.WriteLine(tname + " " + newPC);
                            pc += 2;
                            break;
                        }
                    case Icode_VAR_INC_DEC:
                    case Icode_NAME_INC_DEC:
                    case Icode_PROP_INC_DEC:
                    case Icode_ELEM_INC_DEC:
                    case Icode_REF_INC_DEC:
                        {
                            int incrDecrType = iCode[pc];
                            Console.WriteLine(tname + " " + incrDecrType);
                            ++pc;
                            break;
                        }

                    case Icode_CALLSPECIAL:
                        {
                            int callType = iCode[pc] & 0xFF;
                            bool isNew = (iCode[pc + 1] != 0);
                            int line = getIndex(iCode, pc + 2);
                            Console.WriteLine(tname + " " + callType + " " + isNew + " " + indexReg + " " + line);
                            pc += 4;
                            break;
                        }

                    case Token.CATCH_SCOPE:
                        {
                            bool afterFisrtFlag = (iCode[pc] != 0);
                            Console.WriteLine(tname + " " + afterFisrtFlag);
                            ++pc;
                        }
                        break;
                    case Token.REGEXP:
                        Console.WriteLine(tname + " " + idata.itsRegExpLiterals[indexReg]);
                        break;
                    case Token.OBJECTLIT:
                    case Icode_SPARE_ARRAYLIT:
                        Console.WriteLine(tname + " " + idata.literalIds[indexReg]);
                        break;
                    case Icode_CLOSURE_EXPR:
                    case Icode_CLOSURE_STMT:
                        Console.WriteLine(tname + " " + idata.itsNestedFunctions[indexReg]);
                        break;
                    case Token.CALL:
                    case Icode_TAIL_CALL:
                    case Token.REF_CALL:
                    case Token.NEW:
                        Console.WriteLine(tname + ' ' + indexReg);
                        break;
                    case Token.THROW:
                    case Token.YIELD:
                    case Icode_GENERATOR:
                    case Icode_GENERATOR_END:
                        {
                            int line = getIndex(iCode, pc);
                            Console.WriteLine(tname + " : " + line);
                            pc += 2;
                            break;
                        }
                    case Icode_SHORTNUMBER:
                        {
                            int value = getShort(iCode, pc);
                            Console.WriteLine(tname + " " + value);
                            pc += 2;
                            break;
                        }
                    case Icode_INTNUMBER:
                        {
                            int value = getInt(iCode, pc);
                            Console.WriteLine(tname + " " + value);
                            pc += 4;
                            break;
                        }
                    case Token.NUMBER:
                        {
                            double value = idata.itsDoubleTable[indexReg];
                            Console.WriteLine(tname + " " + value);
                            break;
                        }
                    case Icode_LINE:
                        {
                            int line = getIndex(iCode, pc);
                            Console.WriteLine(tname + " : " + line);
                            pc += 2;
                            break;
                        }
                    case Icode_REG_STR1:
                        {
                            String str = strings[0xFF & iCode[pc]];
                            Console.WriteLine(tname + " \"" + str + '"');
                            ++pc;
                            break;
                        }
                    case Icode_REG_STR2:
                        {
                            String str = strings[getIndex(iCode, pc)];
                            Console.WriteLine(tname + " \"" + str + '"');
                            pc += 2;
                            break;
                        }
                    case Icode_REG_STR4:
                        {
                            String str = strings[getInt(iCode, pc)];
                            Console.WriteLine(tname + " \"" + str + '"');
                            pc += 4;
                            break;
                        }
                    case Icode_REG_IND_C0:
                        indexReg = 0;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND_C1:
                        indexReg = 1;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND_C2:
                        indexReg = 2;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND_C3:
                        indexReg = 3;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND_C4:
                        indexReg = 4;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND_C5:
                        indexReg = 5;
                        Console.WriteLine(tname);
                        break;
                    case Icode_REG_IND1:
                        {
                            indexReg = 0xFF & iCode[pc];
                            Console.WriteLine(tname + " " + indexReg);
                            ++pc;
                            break;
                        }
                    case Icode_REG_IND2:
                        {
                            indexReg = getIndex(iCode, pc);
                            Console.WriteLine(tname + " " + indexReg);
                            pc += 2;
                            break;
                        }
                    case Icode_REG_IND4:
                        {
                            indexReg = getInt(iCode, pc);
                            Console.WriteLine(tname + " " + indexReg);
                            pc += 4;
                            break;
                        }
                    case Icode_GETVAR1:
                    case Icode_SETVAR1:
                    case Icode_SETCONSTVAR1:
                        indexReg = iCode[pc];
                        Console.WriteLine(tname + " " + indexReg);
                        ++pc;
                        break;
                }
                if (old_pc + icodeLength != pc) Kit.codeBug();
            }

            int[] table = idata.itsExceptionTable;
            if (table != null)
            {
                Console.WriteLine("Exception handlers: "
                             + table.Length / EXCEPTION_SLOT_SIZE);
                for (int i = 0; i != table.Length;
                     i += EXCEPTION_SLOT_SIZE)
                {
                    int tryStart = table[i + EXCEPTION_TRY_START_SLOT];
                    int tryEnd = table[i + EXCEPTION_TRY_END_SLOT];
                    int handlerStart = table[i + EXCEPTION_HANDLER_SLOT];
                    int type = table[i + EXCEPTION_TYPE_SLOT];
                    int exceptionLocal = table[i + EXCEPTION_LOCAL_SLOT];
                    int scopeLocal = table[i + EXCEPTION_SCOPE_SLOT];

                    Console.WriteLine(" tryStart=" + tryStart + " tryEnd=" + tryEnd
                                + " handlerStart=" + handlerStart
                                + " type=" + (type == 0 ? "catch" : "finally")
                                + " exceptionLocal=" + exceptionLocal);
                }
            }

        }

        private static String bytecodeName(int bytecode)
        {
            if (!validBytecode(bytecode))
            {
                throw new ArgumentException((bytecode).ToString());
            }

            if (!Token.printICode)
            {
                return (bytecode).ToString();
            }

            if (validTokenCode(bytecode))
            {
                return Token.name(bytecode);
            }

            switch (bytecode)
            {
                case Icode_DUP: return "DUP";
                case Icode_DUP2: return "DUP2";
                case Icode_SWAP: return "SWAP";
                case Icode_POP: return "POP";
                case Icode_POP_RESULT: return "POP_RESULT";
                case Icode_IFEQ_POP: return "IFEQ_POP";
                case Icode_VAR_INC_DEC: return "VAR_INC_DEC";
                case Icode_NAME_INC_DEC: return "NAME_INC_DEC";
                case Icode_PROP_INC_DEC: return "PROP_INC_DEC";
                case Icode_ELEM_INC_DEC: return "ELEM_INC_DEC";
                case Icode_REF_INC_DEC: return "REF_INC_DEC";
                case Icode_SCOPE_LOAD: return "SCOPE_LOAD";
                case Icode_SCOPE_SAVE: return "SCOPE_SAVE";
                case Icode_TYPEOFNAME: return "TYPEOFNAME";
                case Icode_NAME_AND_THIS: return "NAME_AND_THIS";
                case Icode_PROP_AND_THIS: return "PROP_AND_THIS";
                case Icode_ELEM_AND_THIS: return "ELEM_AND_THIS";
                case Icode_VALUE_AND_THIS: return "VALUE_AND_THIS";
                case Icode_CLOSURE_EXPR: return "CLOSURE_EXPR";
                case Icode_CLOSURE_STMT: return "CLOSURE_STMT";
                case Icode_CALLSPECIAL: return "CALLSPECIAL";
                case Icode_RETUNDEF: return "RETUNDEF";
                case Icode_GOSUB: return "GOSUB";
                case Icode_STARTSUB: return "STARTSUB";
                case Icode_RETSUB: return "RETSUB";
                case Icode_LINE: return "LINE";
                case Icode_SHORTNUMBER: return "SHORTNUMBER";
                case Icode_INTNUMBER: return "INTNUMBER";
                case Icode_LITERAL_NEW: return "LITERAL_NEW";
                case Icode_LITERAL_SET: return "LITERAL_SET";
                case Icode_SPARE_ARRAYLIT: return "SPARE_ARRAYLIT";
                case Icode_REG_IND_C0: return "REG_IND_C0";
                case Icode_REG_IND_C1: return "REG_IND_C1";
                case Icode_REG_IND_C2: return "REG_IND_C2";
                case Icode_REG_IND_C3: return "REG_IND_C3";
                case Icode_REG_IND_C4: return "REG_IND_C4";
                case Icode_REG_IND_C5: return "REG_IND_C5";
                case Icode_REG_IND1: return "LOAD_IND1";
                case Icode_REG_IND2: return "LOAD_IND2";
                case Icode_REG_IND4: return "LOAD_IND4";
                case Icode_REG_STR_C0: return "REG_STR_C0";
                case Icode_REG_STR_C1: return "REG_STR_C1";
                case Icode_REG_STR_C2: return "REG_STR_C2";
                case Icode_REG_STR_C3: return "REG_STR_C3";
                case Icode_REG_STR1: return "LOAD_STR1";
                case Icode_REG_STR2: return "LOAD_STR2";
                case Icode_REG_STR4: return "LOAD_STR4";
                case Icode_GETVAR1: return "GETVAR1";
                case Icode_SETVAR1: return "SETVAR1";
                case Icode_UNDEF: return "UNDEF";
                case Icode_ZERO: return "ZERO";
                case Icode_ONE: return "ONE";
                case Icode_ENTERDQ: return "ENTERDQ";
                case Icode_LEAVEDQ: return "LEAVEDQ";
                case Icode_TAIL_CALL: return "TAIL_CALL";
                case Icode_LOCAL_CLEAR: return "LOCAL_CLEAR";
                case Icode_LITERAL_GETTER: return "LITERAL_GETTER";
                case Icode_LITERAL_SETTER: return "LITERAL_SETTER";
                case Icode_SETCONST: return "SETCONST";
                case Icode_SETCONSTVAR: return "SETCONSTVAR";
                case Icode_SETCONSTVAR1: return "SETCONSTVAR1";
                case Icode_GENERATOR: return "GENERATOR";
                case Icode_GENERATOR_END: return "GENERATOR_END";
                case Icode_DEBUGGER: return "DEBUGGER";
            }

            // icode without name
            throw new Exception(bytecode.ToString());
        }

        private void generateFunctionICode()
        {
            itsInFunctionFlag = true;

            FunctionNode theFunction = (FunctionNode)scriptOrFn;

            itsData.itsFunctionType = theFunction.getFunctionType();
            itsData.itsNeedsActivation = theFunction.requiresActivation();
            itsData.itsName = theFunction.getFunctionName();
            if (!theFunction.getIgnoreDynamicScope())
            {
                if (compilerEnv.isUseDynamicScope())
                {
                    itsData.useDynamicScope = true;
                }
            }
            if (theFunction.isGenerator())
            {
                addIcode(Icode_GENERATOR);
                addUint16(theFunction.getBaseLineno() & 0xFFFF);
            }

            generateICodeFromTree(theFunction.getLastChild());
        }


        public static Object interpret(InterpretedFunction ifun,
                             Context cx, Scriptable scope,
                             Scriptable thisObj, Object[] args)
        {
            if (!ScriptRuntime.hasTopCall(cx)) Kit.codeBug();

            if (cx.interpreterSecurityDomain != ifun.securityDomain)
            {
                Object savedDomain = cx.interpreterSecurityDomain;
                cx.interpreterSecurityDomain = ifun.securityDomain;
                try
                {
                    return ifun.securityController.callWithDomain(
                        ifun.securityDomain, cx, ifun, scope, thisObj, args);
                }
                finally
                {
                    cx.interpreterSecurityDomain = savedDomain;
                }
            }

            CallFrame frame = new CallFrame();
            initFrame(cx, scope, thisObj, args, null, 0, args.Length,
                      ifun, null, frame);
            frame.isContinuationsTopFrame = cx.isContinuationsTopCall;
            cx.isContinuationsTopCall = false;

            return interpretLoop(cx, frame, null);
        }

        private static void enterFrame(Context cx, CallFrame frame, Object[] args,
                                   bool continuationRestart)
        {
            bool usesActivation = frame.idata.itsNeedsActivation;
            bool isDebugged = frame.debuggerFrame != null;
            if (usesActivation || isDebugged)
            {
                Scriptable scope = frame.scope;
                if (scope == null)
                {
                    Kit.codeBug();
                }
                else if (continuationRestart)
                {
                    // Walk the parent chain of frame.scope until a NativeCall is 
                    // found. Normally, frame.scope is a NativeCall when called 
                    // from initFrame() for a debugged or activatable function. 
                    // However, when called from interpretLoop() as part of
                    // restarting a continuation, it can also be a NativeWith if 
                    // the continuation was captured within a "with" or "catch" 
                    // block ("catch" implicitly uses NativeWith to create a scope 
                    // to expose the exception variable).
                    for (; ; )
                    {
                        if (scope is NativeWith)
                        {
                            scope = scope.getParentScope();
                            if (scope == null || (frame.parentFrame != null &&
                                                  frame.parentFrame.scope == scope))
                            {
                                // If we get here, we didn't find a NativeCall in 
                                // the call chain before reaching parent frame's 
                                // scope. This should not be possible.
                                Kit.codeBug();
                                break; // Never reached, but keeps the static analyzer happy about "scope" not being null 5 lines above.
                            }
                        }
                        else
                        {
                            break;
                        }
                    }
                }
                if (isDebugged)
                {
                    frame.debuggerFrame.onEnter(cx, scope, frame.thisObj, args);
                }
                // Enter activation only when itsNeedsActivation true, 
                // since debugger should not interfere with activation 
                // chaining
                if (usesActivation)
                {
                    ScriptRuntime.enterActivationFunction(cx, scope);
                }
            }
        }

        private static bool isFrameEnterExitRequired(CallFrame frame)
        {
            return frame.debuggerFrame != null || frame.idata.itsNeedsActivation;
        }


        private static CallFrame processThrowable(Context cx, Object throwable,
                                           CallFrame frame, int indexReg,
                                           bool instructionCounting)
        {
            // Recovering from exception, indexReg contains
            // the index of handler

            if (indexReg >= 0)
            {
                // Normal exception handler, transfer
                // control appropriately

                if (frame.frozen)
                {
                    // XXX Deal with exceptios!!!
                    frame = frame.cloneFrozen();
                }

                int[] table = frame.idata.itsExceptionTable;

                frame.pc = table[indexReg + EXCEPTION_HANDLER_SLOT];
                if (instructionCounting)
                {
                    frame.pcPrevBranch = frame.pc;
                }

                frame.savedStackTop = frame.emptyStackTop;
                int scopeLocal = frame.localShift
                                 + table[indexReg
                                         + EXCEPTION_SCOPE_SLOT];
                int exLocal = frame.localShift
                                 + table[indexReg
                                         + EXCEPTION_LOCAL_SLOT];
                frame.scope = (Scriptable)frame.stack[scopeLocal];
                frame.stack[exLocal] = throwable;

                throwable = null;
            }
            else
            {
                // Continuation restoration
                ContinuationJump cjump = (ContinuationJump)throwable;

                // Clear throwable to indicate that exceptions are OK
                throwable = null;

                if (cjump.branchFrame != frame) Kit.codeBug();

                // Check that we have at least one frozen frame
                // in the case of detached continuation restoration:
                // unwind code ensure that
                if (cjump.capturedFrame == null) Kit.codeBug();

                // Need to rewind branchFrame, capturedFrame
                // and all frames in between
                int rewindCount = cjump.capturedFrame.frameIndex + 1;
                if (cjump.branchFrame != null)
                {
                    rewindCount -= cjump.branchFrame.frameIndex;
                }

                int enterCount = 0;
                CallFrame[] enterFrames = null;

                CallFrame x = cjump.capturedFrame;
                for (int i = 0; i != rewindCount; ++i)
                {
                    if (!x.frozen) Kit.codeBug();
                    if (isFrameEnterExitRequired(x))
                    {
                        if (enterFrames == null)
                        {
                            // Allocate enough space to store the rest
                            // of rewind frames in case all of them
                            // would require to enter
                            enterFrames = new CallFrame[rewindCount
                                                        - i];
                        }
                        enterFrames[enterCount] = x;
                        ++enterCount;
                    }
                    x = x.parentFrame;
                }

                while (enterCount != 0)
                {
                    // execute enter: walk enterFrames in the reverse
                    // order since they were stored starting from
                    // the capturedFrame, not branchFrame
                    --enterCount;
                    x = enterFrames[enterCount];
                    enterFrame(cx, x, ScriptRuntime.emptyArgs, true);
                }

                // Continuation jump is almost done: capturedFrame
                // points to the call to the function that captured
                // continuation, so clone capturedFrame and
                // emulate return that function with the suplied result
                frame = cjump.capturedFrame.cloneFrozen();
                setCallResult(frame, cjump.result, cjump.resultDbl);
                // restart the execution
            }
            frame.throwable = throwable;
            return frame;
        }

        private static void setCallResult(CallFrame frame,
                                     Object callResult,
                                     double callResultDbl)
        {
            if (frame.savedCallOp == Token.CALL)
            {
                frame.stack[frame.savedStackTop] = callResult;
                frame.sDbl[frame.savedStackTop] = callResultDbl;
            }
            else if (frame.savedCallOp == Token.NEW)
            {
                // If construct returns scriptable,
                // then it replaces on stack top saved original instance
                // of the object.
                if (callResult is Scriptable)
                {
                    frame.stack[frame.savedStackTop] = callResult;
                }
            }
            else
            {
                Kit.codeBug();
            }
            frame.savedCallOp = 0;
        }



        private static CallFrame captureFrameForGenerator(CallFrame frame)
        {
            frame.frozen = true;
            CallFrame result = frame.cloneFrozen();
            frame.frozen = false;

            // now isolate this frame from its previous context
            result.parentFrame = null;
            result.frameIndex = 0;

            return result;
        }


        private static Object freezeGenerator(Context cx, CallFrame frame,
                                          int stackTop,
                                          GeneratorState generatorState)
        {
            if (generatorState.operation == NativeGenerator.GENERATOR_CLOSE)
            {
                // Error: no yields when generator is closing
                throw ScriptRuntime.typeError0("msg.yield.closing");
            }
            // return to our caller (which should be a method of NativeGenerator)
            frame.frozen = true;
            frame.result = frame.stack[stackTop];
            frame.resultDbl = frame.sDbl[stackTop];
            frame.savedStackTop = stackTop;
            frame.pc--; // we want to come back here when we resume
            ScriptRuntime.exitActivationFunction(cx);
            return (frame.result != UniqueTag.DOUBLE_MARK)
                ? frame.result
                : ScriptRuntime.wrapNumber(frame.resultDbl);
        }

        private static Object thawGenerator(CallFrame frame, int stackTop,
                                            GeneratorState generatorState, int op)
        {
            // we are resuming execution
            frame.frozen = false;
            int sourceLine = getIndex(frame.idata.itsICode, frame.pc);
            frame.pc += 2; // skip line number data
            if (generatorState.operation == NativeGenerator.GENERATOR_THROW)
            {
                // processing a call to <generator>.throw(exception): must
                // act as if exception was thrown from resumption point
                return new JavaScriptException(generatorState.value,
                                                    frame.idata.itsSourceFile,
                                                    sourceLine);
            }
            if (generatorState.operation == NativeGenerator.GENERATOR_CLOSE)
            {
                return generatorState.value;
            }
            if (generatorState.operation != NativeGenerator.GENERATOR_SEND)
                throw Kit.codeBug();
            if (op == Token.YIELD)
                frame.stack[stackTop] = generatorState.value;
            return ScriptableObject.NOT_FOUND;
        }

        private static int stack_int32(CallFrame frame, int i)
        {
            Object x = frame.stack[i];
            double value;
            if (x == UniqueTag.DOUBLE_MARK)
            {
                value = frame.sDbl[i];
            }
            else
            {
                value = ScriptRuntime.toNumber(x);
            }
            return ScriptRuntime.toInt32(value);
        }

        private static double stack_double(CallFrame frame, int i)
        {
            Object x = frame.stack[i];
            if (x != UniqueTag.DOUBLE_MARK)
            {
                return ScriptRuntime.toNumber(x);
            }
            else
            {
                return frame.sDbl[i];
            }
        }

        private static bool stack_boolean(CallFrame frame, int i)
        {
            Object x = frame.stack[i];

            return ScriptRuntime.toBoolean(x);

        }

        private static void do_add(Object[] stack, double[] sDbl, int stackTop,
                                  Context cx)
        {
            Object rhs = stack[stackTop + 1];
            Object lhs = stack[stackTop];
            double d;
            bool leftRightOrder;
            if (rhs == UniqueTag.DOUBLE_MARK)
            {
                d = sDbl[stackTop + 1];
                if (lhs == UniqueTag.DOUBLE_MARK)
                {
                    sDbl[stackTop] += d;
                    return;
                }
                leftRightOrder = true;
                // fallthrough to object + number code
            }
            else if (lhs == UniqueTag.DOUBLE_MARK)
            {
                d = sDbl[stackTop];
                lhs = rhs;
                leftRightOrder = false;
                // fallthrough to object + number code
            }
            else
            {
                if (lhs is Scriptable || rhs is Scriptable)
                {
                    stack[stackTop] = ScriptRuntime.add(lhs, rhs, cx);
                }
                else if (lhs is String)
                {
                    String lstr = (String)lhs;
                    String rstr = ScriptRuntime.toString(rhs);
                    stack[stackTop] = lstr + rstr;
                }
                else if (rhs is String)
                {
                    String lstr = ScriptRuntime.toString(lhs);
                    String rstr = (String)rhs;
                    stack[stackTop] = lstr + rstr;
                }
                else
                {
                    double lDbl = ScriptRuntime.toNumber(lhs);
                    double rDbl = ScriptRuntime.toNumber(rhs);
                    stack[stackTop] = UniqueTag.DOUBLE_MARK;
                    sDbl[stackTop] = lDbl + rDbl;
                }
                return;
            }

            // handle object(lhs) + number(d) code
            if (lhs is Scriptable)
            {
                rhs = ScriptRuntime.wrapNumber(d);
                if (!leftRightOrder)
                {
                    Object tmp = lhs;
                    lhs = rhs;
                    rhs = tmp;
                }
                stack[stackTop] = ScriptRuntime.add(lhs, rhs, cx);
            }
            else if (lhs is String)
            {
                String lstr = (String)lhs;
                String rstr = ScriptRuntime.toString(d);
                if (leftRightOrder)
                {
                    stack[stackTop] = lstr + rstr;
                }
                else
                {
                    stack[stackTop] = rstr + lstr;
                }
            }
            else
            {
                double lDbl = ScriptRuntime.toNumber(lhs);
                stack[stackTop] = UniqueTag.DOUBLE_MARK;
                sDbl[stackTop] = lDbl + d;
            }
        }

        private static void addInstructionCount(Context cx, CallFrame frame,
                                            int extra)
        {
            cx.instructionCount += frame.pc - frame.pcPrevBranch + extra;
            if (cx.instructionCount > cx.instructionThreshold)
            {
                cx.observeInstructionCount(cx.instructionCount);
                cx.instructionCount = 0;
            }
        }


        private static void exitFrame(Context cx, CallFrame frame,
                                  Object throwable)
        {
            if (frame.idata.itsNeedsActivation)
            {
                ScriptRuntime.exitActivationFunction(cx);
            }

            if (frame.debuggerFrame != null)
            {
                try
                {
                    if (throwable is Exception)
                    {
                        frame.debuggerFrame.onExit(cx, true, throwable);
                    }
                    else
                    {
                        Object result;
                        ContinuationJump cjump = (ContinuationJump)throwable;
                        if (cjump == null)
                        {
                            result = frame.result;
                        }
                        else
                        {
                            result = cjump.result;
                        }
                        if (result == UniqueTag.DOUBLE_MARK)
                        {
                            double resultDbl;
                            if (cjump == null)
                            {
                                resultDbl = frame.resultDbl;
                            }
                            else
                            {
                                resultDbl = cjump.resultDbl;
                            }
                            result = ScriptRuntime.wrapNumber(resultDbl);
                        }
                        frame.debuggerFrame.onExit(cx, false, result);
                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(
     "RHINO USAGE WARNING: onExit terminated with exception");
                    //ex.printStackTrace(System.err);
                }
            }
        }

        private static bool shallowEquals(Object[] stack, double[] sDbl,
            int stackTop)
        {
            Object rhs = stack[stackTop + 1];
            Object lhs = stack[stackTop];
            Object DBL_MRK = UniqueTag.DOUBLE_MARK;
            double rdbl, ldbl;
            if (rhs == DBL_MRK)
            {
                rdbl = sDbl[stackTop + 1];
                if (lhs == DBL_MRK)
                {
                    ldbl = sDbl[stackTop];
                }
                else if (ScriptRuntime.isNumber(lhs))
                {
                    ldbl = ScriptRuntime.toNumber(lhs);
                }
                else
                {
                    return false;
                }
            }
            else if (lhs == DBL_MRK)
            {
                ldbl = sDbl[stackTop];
                if (rhs == DBL_MRK)
                {
                    rdbl = sDbl[stackTop + 1];
                }
                else if (ScriptRuntime.isNumber(rhs))
                {
                    rdbl = ScriptRuntime.toNumber(rhs);
                }
                else
                {
                    return false;
                }
            }
            else
            {
                return ScriptRuntime.shallowEq(lhs, rhs);
            }
            return (ldbl == rdbl);
        }


        private static CallFrame initFrameForNoSuchMethod(Context cx,
            CallFrame frame, int indexReg, Object[] stack, double[] sDbl,
            int stackTop, int op, Scriptable funThisObj, Scriptable calleeScope,
            RoughJs.Ast.ScriptRuntime.NoSuchMethodShim noSuchMethodShim, InterpretedFunction ifun)
        {
            // create an args array from the stack
            Object[] argsArray = null;
            // exactly like getArgsArray except that the first argument
            // is the method name from the shim
            int shift = stackTop + 2;
            Object[] elements = new Object[indexReg];
            for (int i = 0; i < indexReg; ++i, ++shift)
            {
                Object val = stack[shift];
                if (val == UniqueTag.DOUBLE_MARK)
                {
                    val = ScriptRuntime.wrapNumber(sDbl[shift]);
                }
                elements[i] = val;
            }
            argsArray = new Object[2];
            argsArray[0] = noSuchMethodShim.methodName;
            argsArray[1] = cx.newArray(calleeScope, elements);

            // exactly the same as if it's a regular InterpretedFunction
            CallFrame callParentFrame = frame;
            CallFrame calleeFrame = new CallFrame();
            if (op == Icode_TAIL_CALL)
            {
                callParentFrame = frame.parentFrame;
                exitFrame(cx, frame, null);
            }
            // init the frame with the underlying method with the 
            // adjusted args array and shim's function
            initFrame(cx, calleeScope, funThisObj, argsArray, null,
              0, 2, ifun, callParentFrame, calleeFrame);
            if (op != Icode_TAIL_CALL)
            {
                frame.savedStackTop = stackTop;
                frame.savedCallOp = op;
            }
            return calleeFrame;
        }


        private static Object interpretLoop(Context cx, CallFrame frame,
                                       Object throwable)
        {
            // throwable holds exception object to rethrow or catch
            // It is also used for continuation restart in which case
            // it holds ContinuationJump

            Object DBL_MRK = UniqueTag.DOUBLE_MARK;
            Object undefined = Undefined.instance;

            bool instructionCounting = (cx.instructionThreshold != 0);
            // arbitrary number to add to instructionCount when calling
            // other functions
            int INVOCATION_COST = 100;
            // arbitrary exception cost for instruction counting
            int EXCEPTION_COST = 100;

            String stringReg = null;
            int indexReg = -1;

            if (cx.lastInterpreterFrame != null)
            {
                // save the top frame from the previous interpretLoop
                // invocation on the stack
                if (cx.previousInterpreterInvocations == null)
                {
                    cx.previousInterpreterInvocations = new ObjArray();
                }
                cx.previousInterpreterInvocations.push(cx.lastInterpreterFrame);
            }

            // When restarting continuation throwable is not null and to jump
            // to the code that rewind continuation state indexReg should be set
            // to -1.
            // With the normal call throwable == null and indexReg == -1 allows to
            // catch bugs with using indeReg to access array elements before
            // initializing indexReg.

            GeneratorState generatorState = null;
            if (throwable != null)
            {
                if (throwable is GeneratorState)
                {
                    generatorState = (GeneratorState)throwable;

                    // reestablish this call frame
                    enterFrame(cx, frame, ScriptRuntime.emptyArgs, true);
                    throwable = null;
                }
                else if (!(throwable is ContinuationJump))
                {
                    // It should be continuation
                    Kit.codeBug();
                }
            }

            Object interpreterResult = null;
            double interpreterResultDbl = 0.0;

        StateLoop: for (; ; )
            {
            withoutExceptions:
                try
                {

                    if (throwable != null)
                    {
                        // Need to return both 'frame' and 'throwable' from
                        // 'processThrowable', so just added a 'throwable'
                        // member in 'frame'.
                        frame = processThrowable(cx, throwable, frame, indexReg,
                                                 instructionCounting);
                        throwable = frame.throwable;
                        frame.throwable = null;
                    }
                    else
                    {
                        if (generatorState == null && frame.frozen) Kit.codeBug();
                    }

                    // Use local variables for constant values in frame
                    // for faster access
                    Object[] stack = frame.stack;
                    double[] sDbl = frame.sDbl;
                    Object[] vars = frame.varSource.stack;
                    double[] varDbls = frame.varSource.sDbl;
                    int[] varAttributes = frame.varSource.stackAttributes;
                    sbyte[] iCode = frame.idata.itsICode;
                    String[] strings = frame.idata.itsStringTable;

                    // Use local for stackTop as well. Since execption handlers
                    // can only exist at statement level where stack is empty,
                    // it is necessary to save/restore stackTop only across
                    // function calls and normal returns.
                    int stackTop = frame.savedStackTop;

                    // Store new frame in cx which is used for error reporting etc.
                    cx.lastInterpreterFrame = frame;

                Loop: for (; ; )
                    {

                        // Exception handler assumes that PC is already incremented
                        // pass the instruction start when it searches the
                        // exception handler
                        int op = iCode[frame.pc++];
                    jumplessRun:
                        {

                            // Back indent to ease implementation reading
                            switch (op)
                            {
                                case Icode_GENERATOR:
                                    {
                                        if (!frame.frozen)
                                        {
                                            // First time encountering this opcode: create new generator
                                            // object and return
                                            frame.pc--; // we want to come back here when we resume
                                            CallFrame generatorFrame = captureFrameForGenerator(frame);
                                            generatorFrame.frozen = true;
                                            NativeGenerator generator = new NativeGenerator(frame.scope,
                                                generatorFrame.fnOrScript, generatorFrame);
                                            frame.result = generator;
                                            goto Loop1;
                                        }
                                        else
                                        {
                                            // We are now resuming execution. Fall through to YIELD case.
                                            goto case Token.YIELD;
                                        }
                                    }
                                // fall through...
                                case Token.YIELD:
                                    {
                                        if (!frame.frozen)
                                        {
                                            return freezeGenerator(cx, frame, stackTop, generatorState);
                                        }
                                        else
                                        {
                                            Object obj = thawGenerator(frame, stackTop, generatorState, op);
                                            if (obj != ScriptableObject.NOT_FOUND)
                                            {
                                                throwable = obj;
                                                goto withoutExceptions1;
                                            }
                                            goto Loop;
                                        }
                                    }
                                case Icode_GENERATOR_END:
                                    {
                                        // throw StopIteration
                                        frame.frozen = true;
                                        int sourceLine = getIndex(iCode, frame.pc);
                                        generatorState.returnedException = new JavaScriptException(
                                            NativeIterator.getStopIterationObject(frame.scope),
                                            frame.idata.itsSourceFile, sourceLine);
                                        goto Loop1;
                                    }
                                case Token.THROW:
                                    {
                                        Object value = stack[stackTop];
                                        if (value == DBL_MRK) value = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;

                                        int sourceLine = getIndex(iCode, frame.pc);
                                        throwable = new JavaScriptException(value,
                                                                            frame.idata.itsSourceFile,
                                                                            sourceLine);
                                        goto withoutExceptions1;
                                    }
                                case Token.RETHROW:
                                    {
                                        indexReg += frame.localShift;
                                        throwable = stack[indexReg];
                                        goto withoutExceptions1;
                                    }
                                case Token.GE:
                                case Token.LE:
                                case Token.GT:
                                case Token.LT:
                                    {
                                        --stackTop;
                                        Object rhs = stack[stackTop + 1];
                                        Object lhs = stack[stackTop];
                                        bool valBln;




                                        double rDbl, lDbl;
                                        if (rhs == DBL_MRK)
                                        {
                                            rDbl = sDbl[stackTop + 1];
                                            lDbl = stack_double(frame, stackTop);
                                        }
                                        else if (lhs == DBL_MRK)
                                        {
                                            rDbl = ScriptRuntime.toNumber(rhs);
                                            lDbl = sDbl[stackTop];
                                        }
                                        else
                                        {
                                            goto number_compare;
                                        }
                                        switch (op)
                                        {
                                            case Token.GE:
                                                valBln = (lDbl >= rDbl);
                                                goto object_compare;
                                            case Token.LE:
                                                valBln = (lDbl <= rDbl);
                                                goto object_compare;
                                            case Token.GT:
                                                valBln = (lDbl > rDbl);
                                                goto object_compare;
                                            case Token.LT:
                                                valBln = (lDbl < rDbl);
                                                goto object_compare;
                                            default:
                                                throw Kit.codeBug();
                                        }

                                    number_compare: ;
                                        switch (op)
                                        {
                                            case Token.GE:
                                                valBln = ScriptRuntime.cmp_LE(rhs, lhs);
                                                break;
                                            case Token.LE:
                                                valBln = ScriptRuntime.cmp_LE(lhs, rhs);
                                                break;
                                            case Token.GT:
                                                valBln = ScriptRuntime.cmp_LT(rhs, lhs);
                                                break;
                                            case Token.LT:
                                                valBln = ScriptRuntime.cmp_LT(lhs, rhs);
                                                break;
                                            default:
                                                throw Kit.codeBug();
                                        }

                                    object_compare: ;
                                        stack[stackTop] = ScriptRuntime.wrapBoolean(valBln);
                                        goto Loop;
                                    }
                                case Token.IN:
                                case Token.INSTANCEOF:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        bool valBln;
                                        if (op == Token.IN)
                                        {
                                            valBln = ScriptRuntime.in1(lhs, rhs, cx);
                                        }
                                        else
                                        {
                                            valBln = ScriptRuntime.instanceOf(lhs, rhs, cx);
                                        }
                                        stack[stackTop] = ScriptRuntime.wrapBoolean(valBln);
                                        goto Loop;
                                    }
                                case Token.EQ:
                                case Token.NE:
                                    {//==计算
                                        --stackTop;
                                        bool valBln;
                                        Object rhs = stack[stackTop + 1];
                                        Object lhs = stack[stackTop];
                                        if (rhs == DBL_MRK)
                                        {
                                            if (lhs == DBL_MRK)
                                            {
                                                valBln = (sDbl[stackTop] == sDbl[stackTop + 1]);
                                            }
                                            else
                                            {
                                                valBln = ScriptRuntime.eqNumber(sDbl[stackTop + 1], lhs);
                                            }
                                        }
                                        else
                                        {
                                            if (lhs == DBL_MRK)
                                            {
                                                valBln = ScriptRuntime.eqNumber(sDbl[stackTop], rhs);
                                            }
                                            else
                                            {
                                                valBln = ScriptRuntime.eq(lhs, rhs);
                                            }
                                        }
                                        valBln ^= (op == Token.NE);
                                        stack[stackTop] = ScriptRuntime.wrapBoolean(valBln);
                                        goto Loop;
                                    }
                                case Token.SHEQ:
                                case Token.SHNE:
                                    {
                                        --stackTop;
                                        bool valBln = shallowEquals(stack, sDbl, stackTop);
                                        valBln ^= (op == Token.SHNE);
                                        stack[stackTop] = ScriptRuntime.wrapBoolean(valBln);
                                        goto Loop;
                                    }
                                case Token.IFNE:
                                    if (stack_boolean(frame, stackTop--))
                                    {
                                        frame.pc += 2;
                                        goto Loop;
                                    }
                                    goto jumplessRun1; ;
                                case Token.IFEQ:
                                    if (!stack_boolean(frame, stackTop--))
                                    {
                                        frame.pc += 2;
                                        goto Loop;
                                    }
                                    goto jumplessRun1; ;
                                case Icode_IFEQ_POP:
                                    if (!stack_boolean(frame, stackTop--))
                                    {
                                        frame.pc += 2;
                                        goto Loop;
                                    }
                                    stack[stackTop--] = null;
                                    goto jumplessRun1; ;
                                case Token.GOTO:
                                    goto jumplessRun1; ;
                                case Icode_GOSUB:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = frame.pc + 2;
                                    goto jumplessRun1; ;
                                case Icode_STARTSUB:
                                    if (stackTop == frame.emptyStackTop + 1)
                                    {
                                        // Call from Icode_GOSUB: store return PC address in the local
                                        indexReg += frame.localShift;
                                        stack[indexReg] = stack[stackTop];
                                        sDbl[indexReg] = sDbl[stackTop];
                                        --stackTop;
                                    }
                                    else
                                    {
                                        // Call from exception handler: exception object is already stored
                                        // in the local
                                        if (stackTop != frame.emptyStackTop) Kit.codeBug();
                                    }
                                    goto Loop;
                                case Icode_RETSUB:
                                    {
                                        // indexReg: local to store return address
                                        if (instructionCounting)
                                        {
                                            addInstructionCount(cx, frame, 0);
                                        }
                                        indexReg += frame.localShift;
                                        Object value = stack[indexReg];
                                        if (value != DBL_MRK)
                                        {
                                            // Invocation from exception handler, restore object to rethrow
                                            throwable = value;
                                            goto withoutExceptions1;
                                        }
                                        // Normal return from GOSUB
                                        frame.pc = (int)sDbl[indexReg];
                                        if (instructionCounting)
                                        {
                                            frame.pcPrevBranch = frame.pc;
                                        }
                                        goto Loop;
                                    }
                                case Icode_POP:
                                    stack[stackTop] = null;
                                    stackTop--;
                                    goto Loop;
                                case Icode_POP_RESULT:
                                    frame.result = stack[stackTop];
                                    frame.resultDbl = sDbl[stackTop];
                                    stack[stackTop] = null;
                                    --stackTop;
                                    goto Loop;
                                case Icode_DUP:
                                    stack[stackTop + 1] = stack[stackTop];
                                    sDbl[stackTop + 1] = sDbl[stackTop];
                                    stackTop++;
                                    goto Loop;
                                case Icode_DUP2:
                                    stack[stackTop + 1] = stack[stackTop - 1];
                                    sDbl[stackTop + 1] = sDbl[stackTop - 1];
                                    stack[stackTop + 2] = stack[stackTop];
                                    sDbl[stackTop + 2] = sDbl[stackTop];
                                    stackTop += 2;
                                    goto Loop;
                                case Icode_SWAP:
                                    {
                                        Object o = stack[stackTop];
                                        stack[stackTop] = stack[stackTop - 1];
                                        stack[stackTop - 1] = o;
                                        double d = sDbl[stackTop];
                                        sDbl[stackTop] = sDbl[stackTop - 1];
                                        sDbl[stackTop - 1] = d;
                                        goto Loop;
                                    }
                                case Token.RETURN:
                                    frame.result = stack[stackTop];
                                    frame.resultDbl = sDbl[stackTop];
                                    --stackTop;
                                    goto Loop1;
                                case Token.RETURN_RESULT:
                                    goto Loop1;
                                case Icode_RETUNDEF:
                                    frame.result = undefined;
                                    goto Loop1;
                                case Token.BITNOT:
                                    {
                                        int rIntValue = stack_int32(frame, stackTop);
                                        stack[stackTop] = DBL_MRK;
                                        sDbl[stackTop] = ~rIntValue;
                                        goto Loop;
                                    }
                                case Token.BITAND:
                                case Token.BITOR:
                                case Token.BITXOR:
                                case Token.LSH:
                                case Token.RSH:
                                    {
                                        int lIntValue = stack_int32(frame, stackTop - 1);
                                        int rIntValue = stack_int32(frame, stackTop);
                                        stack[--stackTop] = DBL_MRK;
                                        switch (op)
                                        {
                                            case Token.BITAND:
                                                lIntValue &= rIntValue;
                                                break;
                                            case Token.BITOR:
                                                lIntValue |= rIntValue;
                                                break;
                                            case Token.BITXOR:
                                                lIntValue ^= rIntValue;
                                                break;
                                            case Token.LSH:
                                                lIntValue <<= rIntValue;
                                                break;
                                            case Token.RSH:
                                                lIntValue >>= rIntValue;
                                                break;
                                        }
                                        sDbl[stackTop] = lIntValue;
                                        goto Loop;
                                    }
                                case Token.URSH:
                                    {
                                        double lDbl = stack_double(frame, stackTop - 1);
                                        int rIntValue = stack_int32(frame, stackTop) & 0x1F;
                                        stack[--stackTop] = DBL_MRK;
                                        sDbl[stackTop] = MathKit.foo2(ScriptRuntime.toUint32(lDbl), rIntValue);
                                        goto Loop;
                                    }
                                case Token.NEG:
                                case Token.POS:
                                    {
                                        double rDbl = stack_double(frame, stackTop);
                                        stack[stackTop] = DBL_MRK;
                                        if (op == Token.NEG)
                                        {
                                            rDbl = -rDbl;
                                        }
                                        sDbl[stackTop] = rDbl;
                                        goto Loop;
                                    }
                                case Token.ADD:
                                    --stackTop;
                                    do_add(stack, sDbl, stackTop, cx);
                                    goto Loop;
                                case Token.SUB:
                                case Token.MUL:
                                case Token.DIV:
                                case Token.MOD:
                                    {
                                        double rDbl = stack_double(frame, stackTop);
                                        --stackTop;
                                        double lDbl = stack_double(frame, stackTop);
                                        stack[stackTop] = DBL_MRK;
                                        switch (op)
                                        {
                                            case Token.SUB:
                                                lDbl -= rDbl;
                                                break;
                                            case Token.MUL:
                                                lDbl *= rDbl;
                                                break;
                                            case Token.DIV:
                                                lDbl /= rDbl;
                                                break;
                                            case Token.MOD:
                                                lDbl %= rDbl;
                                                break;
                                        }
                                        sDbl[stackTop] = lDbl;
                                        goto Loop;
                                    }
                                case Token.NOT:
                                    stack[stackTop] = ScriptRuntime.wrapBoolean(
                                                          !stack_boolean(frame, stackTop));
                                    goto Loop;
                                case Token.BINDNAME:
                                    stack[++stackTop] = ScriptRuntime.bind(cx, frame.scope, stringReg);
                                    goto Loop;
                                case Token.SETNAME:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Scriptable lhs = (Scriptable)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.setName(lhs, rhs, cx,
                                                                                frame.scope, stringReg);
                                        goto Loop;
                                    }
                                case Icode_SETCONST:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Scriptable lhs = (Scriptable)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.setConst(lhs, rhs, cx, stringReg);
                                        goto Loop;
                                    }
                                case Token.DELPROP:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.delete(lhs, rhs, cx);
                                        goto Loop;
                                    }
                                case Token.GETPROPNOWARN:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.getObjectPropNoWarn(lhs, stringReg, cx);
                                        goto Loop;
                                    }
                                case Token.GETPROP:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.getObjectProp(lhs, stringReg, cx, frame.scope);
                                        goto Loop;
                                    }
                                case Token.SETPROP:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.setObjectProp(lhs, stringReg, rhs,
                                                                                      cx);
                                        goto Loop;
                                    }
                                case Icode_PROP_INC_DEC:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.propIncrDecr(lhs, stringReg,
                                                                                     cx, iCode[frame.pc]);
                                        ++frame.pc;
                                        goto Loop;
                                    }
                                case Token.GETELEM:
                                    {
                                        --stackTop;
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK)
                                        {
                                            lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        }
                                        Object value;
                                        Object id = stack[stackTop + 1];
                                        if (id != DBL_MRK)
                                        {
                                            value = ScriptRuntime.getObjectElem(lhs, id, cx, frame.scope);
                                        }
                                        else
                                        {
                                            double d = sDbl[stackTop + 1];
                                            value = ScriptRuntime.getObjectIndex(lhs, d, cx);
                                        }
                                        stack[stackTop] = value;
                                        goto Loop;
                                    }
                                case Token.SETELEM:
                                    {
                                        stackTop -= 2;
                                        Object rhs = stack[stackTop + 2];
                                        if (rhs == DBL_MRK)
                                        {
                                            rhs = ScriptRuntime.wrapNumber(sDbl[stackTop + 2]);
                                        }
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK)
                                        {
                                            lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        }
                                        Object value;
                                        Object id = stack[stackTop + 1];
                                        if (id != DBL_MRK)
                                        {
                                            value = ScriptRuntime.setObjectElem(lhs, id, rhs, cx);
                                        }
                                        else
                                        {
                                            double d = sDbl[stackTop + 1];
                                            value = ScriptRuntime.setObjectIndex(lhs, d, rhs, cx);
                                        }
                                        stack[stackTop] = value;
                                        goto Loop;
                                    }
                                case Icode_ELEM_INC_DEC:
                                    {
                                        Object rhs = stack[stackTop];
                                        if (rhs == DBL_MRK) rhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.elemIncrDecr(lhs, rhs, cx,
                                                                                     iCode[frame.pc]);
                                        ++frame.pc;
                                        goto Loop;
                                    }
                                case Token.GET_REF:
                                    {
                                        Ref ref1 = (Ref)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.refGet(ref1, cx);
                                        goto Loop;
                                    }
                                case Token.SET_REF:
                                    {
                                        Object value = stack[stackTop];
                                        if (value == DBL_MRK) value = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Ref ref1 = (Ref)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.refSet(ref1, value, cx);
                                        goto Loop;
                                    }
                                case Token.DEL_REF:
                                    {
                                        Ref ref1 = (Ref)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.refDel(ref1, cx);
                                        goto Loop;
                                    }
                                case Icode_REF_INC_DEC:
                                    {
                                        Ref ref1 = (Ref)stack[stackTop];
                                        stack[stackTop] = ScriptRuntime.refIncrDecr(ref1, cx, iCode[frame.pc]);
                                        ++frame.pc;
                                        goto Loop;
                                    }
                                case Token.LOCAL_LOAD:
                                    ++stackTop;
                                    indexReg += frame.localShift;
                                    stack[stackTop] = stack[indexReg];
                                    sDbl[stackTop] = sDbl[indexReg];
                                    goto Loop;
                                case Icode_LOCAL_CLEAR:
                                    indexReg += frame.localShift;
                                    stack[indexReg] = null;
                                    goto Loop;
                                case Icode_NAME_AND_THIS:
                                    // stringReg: name
                                    ++stackTop;
                                    stack[stackTop] = ScriptRuntime.getNameFunctionAndThis(stringReg,
                                                                                           cx, frame.scope);
                                    ++stackTop;
                                    stack[stackTop] = ScriptRuntime.lastStoredScriptable(cx);
                                    goto Loop;
                                case Icode_PROP_AND_THIS:
                                    {
                                        Object obj = stack[stackTop];
                                        if (obj == DBL_MRK) obj = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        // stringReg: property
                                        stack[stackTop] = ScriptRuntime.getPropFunctionAndThis(obj, stringReg,
                                                                                               cx, frame.scope);
                                        ++stackTop;
                                        stack[stackTop] = ScriptRuntime.lastStoredScriptable(cx);
                                        goto Loop;
                                    }
                                case Icode_ELEM_AND_THIS:
                                    {
                                        Object obj = stack[stackTop - 1];
                                        if (obj == DBL_MRK) obj = ScriptRuntime.wrapNumber(sDbl[stackTop - 1]);
                                        Object id = stack[stackTop];
                                        if (id == DBL_MRK) id = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop - 1] = ScriptRuntime.getElemFunctionAndThis(obj, id, cx);
                                        stack[stackTop] = ScriptRuntime.lastStoredScriptable(cx);
                                        goto Loop;
                                    }
                                case Icode_VALUE_AND_THIS:
                                    {
                                        Object value = stack[stackTop];
                                        if (value == DBL_MRK) value = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.getValueFunctionAndThis(value, cx);
                                        ++stackTop;
                                        stack[stackTop] = ScriptRuntime.lastStoredScriptable(cx);
                                        goto Loop;
                                    }
                                case Icode_CALLSPECIAL:
                                    {
                                        if (instructionCounting)
                                        {
                                            cx.instructionCount += INVOCATION_COST;
                                        }
                                        int callType = iCode[frame.pc] & 0xFF;
                                        bool isNew = (iCode[frame.pc + 1] != 0);
                                        int sourceLine = getIndex(iCode, frame.pc + 2);

                                        // indexReg: number of arguments
                                        if (isNew)
                                        {
                                            // stack change: function arg0 .. argN -> newResult
                                            stackTop -= indexReg;

                                            Object function = stack[stackTop];
                                            if (function == DBL_MRK)
                                                function = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                            Object[] outArgs = getArgsArray(
                                                                   stack, sDbl, stackTop + 1, indexReg);
                                            stack[stackTop] = ScriptRuntime.newSpecial(
                                                                  cx, function, outArgs, frame.scope, callType);
                                        }
                                        else
                                        {
                                            // stack change: function thisObj arg0 .. argN -> result
                                            stackTop -= 1 + indexReg;

                                            // Call code generation ensure that stack here
                                            // is ... Callable Scriptable
                                            Scriptable functionThis = (Scriptable)stack[stackTop + 1];
                                            Callable function = (Callable)stack[stackTop];
                                            Object[] outArgs = getArgsArray(
                                                                   stack, sDbl, stackTop + 2, indexReg);
                                            stack[stackTop] = ScriptRuntime.callSpecial(
                                                                  cx, function, functionThis, outArgs,
                                                                  frame.scope, frame.thisObj, callType,
                                                                  frame.idata.itsSourceFile, sourceLine);
                                        }
                                        frame.pc += 4;
                                        goto Loop;
                                    }
                                case Token.CALL:
                                case Icode_TAIL_CALL:
                                case Token.REF_CALL:
                                    {
                                        if (instructionCounting)
                                        {
                                            cx.instructionCount += INVOCATION_COST;
                                        }
                                        // stack change: function thisObj arg0 .. argN -> result
                                        // indexReg: number of arguments
                                        stackTop -= 1 + indexReg;

                                        // CALL generation ensures that fun and funThisObj
                                        // are already Scriptable and Callable objects respectively
                                        Callable fun = (Callable)stack[stackTop];
                                        Scriptable funThisObj = (Scriptable)stack[stackTop + 1];
                                        if (op == Token.REF_CALL)
                                        {
                                            Object[] outArgs = getArgsArray(stack, sDbl, stackTop + 2,
                                                                            indexReg);
                                            stack[stackTop] = ScriptRuntime.callRef(fun, funThisObj,
                                                                                    outArgs, cx);
                                            goto Loop;
                                        }
                                        Scriptable calleeScope = frame.scope;
                                        if (frame.useActivation)
                                        {
                                            calleeScope = ScriptableObject.getTopLevelScope(frame.scope);
                                        }
                                        if (fun is InterpretedFunction)
                                        {
                                            InterpretedFunction ifun = (InterpretedFunction)fun;
                                            if (frame.fnOrScript.securityDomain == ifun.securityDomain)
                                            {
                                                CallFrame callParentFrame = frame;
                                                CallFrame calleeFrame = new CallFrame();
                                                if (op == Icode_TAIL_CALL)
                                                {
                                                    // In principle tail call can re-use the current
                                                    // frame and its stack arrays but it is hard to
                                                    // do properly. Any exceptions that can legally
                                                    // happen during frame re-initialization including
                                                    // StackOverflowException during innocent looking
                                                    // Array.Copy may leave the current frame
                                                    // data corrupted leading to undefined behaviour
                                                    // in the catch code bellow that unwinds JS stack
                                                    // on exceptions. Then there is issue about frame release
                                                    // end exceptions there.
                                                    // To avoid frame allocation a released frame
                                                    // can be cached for re-use which would also benefit
                                                    // non-tail calls but it is not clear that this caching
                                                    // would gain in performance due to potentially
                                                    // bad interaction with GC.
                                                    callParentFrame = frame.parentFrame;
                                                    // Release the current frame. See Bug #344501 to see why
                                                    // it is being done here.
                                                    exitFrame(cx, frame, null);
                                                }
                                                initFrame(cx, calleeScope, funThisObj, stack, sDbl,
                                                          stackTop + 2, indexReg, ifun, callParentFrame,
                                                          calleeFrame);
                                                if (op != Icode_TAIL_CALL)
                                                {
                                                    frame.savedStackTop = stackTop;
                                                    frame.savedCallOp = op;
                                                }
                                                frame = calleeFrame;
                                                goto StateLoop;
                                            }
                                        }

                                        if (fun is NativeContinuation)
                                        {
                                            // Jump to the captured continuation
                                            ContinuationJump cjump;
                                            cjump = new ContinuationJump((NativeContinuation)fun, frame);

                                            // continuation result is the first argument if any
                                            // of continuation call
                                            if (indexReg == 0)
                                            {
                                                cjump.result = undefined;
                                            }
                                            else
                                            {
                                                cjump.result = stack[stackTop + 2];
                                                cjump.resultDbl = sDbl[stackTop + 2];
                                            }

                                            // Start the real unwind job
                                            throwable = cjump;
                                            goto withoutExceptions1;
                                        }

                                        if (fun is IdFunctionObject)
                                        {
                                            IdFunctionObject ifun = (IdFunctionObject)fun;
                                            if (NativeContinuation.isContinuationConstructor(ifun))
                                            {
                                                frame.stack[stackTop] = captureContinuation(cx,
                                                        frame.parentFrame, false);
                                                goto Loop;
                                            }
                                            // Bug 405654 -- make best effort to keep Function.apply and 
                                            // Function.call within this interpreter loop invocation
                                            if (BaseFunction.isApplyOrCall(ifun))
                                            {
                                                Callable applyCallable = ScriptRuntime.getCallable(funThisObj);
                                                if (applyCallable is InterpretedFunction)
                                                {
                                                    InterpretedFunction iApplyCallable = (InterpretedFunction)applyCallable;
                                                    if (frame.fnOrScript.securityDomain == iApplyCallable.securityDomain)
                                                    {
                                                        frame = initFrameForApplyOrCall(cx, frame, indexReg,
                                                                stack, sDbl, stackTop, op, calleeScope, ifun,
                                                                iApplyCallable);
                                                        goto StateLoop;
                                                    }
                                                }
                                            }
                                        }

                                        // Bug 447697 -- make best effort to keep __noSuchMethod__ within this  
                                        // interpreter loop invocation
                                        if (fun is RoughJs.Ast.ScriptRuntime.NoSuchMethodShim)
                                        {
                                            // get the shim and the actual method
                                            RoughJs.Ast.ScriptRuntime.NoSuchMethodShim noSuchMethodShim = (RoughJs.Ast.ScriptRuntime.NoSuchMethodShim)fun;
                                            Callable noSuchMethodMethod = noSuchMethodShim.noSuchMethodMethod;
                                            // if the method is in fact an InterpretedFunction
                                            if (noSuchMethodMethod is InterpretedFunction)
                                            {
                                                InterpretedFunction ifun = (InterpretedFunction)noSuchMethodMethod;
                                                if (frame.fnOrScript.securityDomain == ifun.securityDomain)
                                                {
                                                    frame = initFrameForNoSuchMethod(cx, frame, indexReg, stack, sDbl,
                                                                             stackTop, op, funThisObj, calleeScope,
                                                                             noSuchMethodShim, ifun);
                                                    goto StateLoop;
                                                }
                                            }
                                        }

                                        cx.lastInterpreterFrame = frame;
                                        frame.savedCallOp = op;
                                        frame.savedStackTop = stackTop;
                                        stack[stackTop] = fun.call(cx, calleeScope, funThisObj,
                                                getArgsArray(stack, sDbl, stackTop + 2, indexReg));
                                        cx.lastInterpreterFrame = null;

                                        goto Loop;
                                    }
                                case Token.NEW:
                                    {
                                        if (instructionCounting)
                                        {
                                            cx.instructionCount += INVOCATION_COST;
                                        }
                                        // stack change: function arg0 .. argN -> newResult
                                        // indexReg: number of arguments
                                        stackTop -= indexReg;

                                        Object lhs = stack[stackTop];
                                        if (lhs is InterpretedFunction)
                                        {
                                            InterpretedFunction f = (InterpretedFunction)lhs;
                                            if (frame.fnOrScript.securityDomain == f.securityDomain)
                                            {
                                                Scriptable newInstance = f.createObject(cx, frame.scope);
                                                CallFrame calleeFrame = new CallFrame();
                                                initFrame(cx, frame.scope, newInstance, stack, sDbl,
                                                          stackTop + 1, indexReg, f, frame,
                                                          calleeFrame);

                                                stack[stackTop] = newInstance;
                                                frame.savedStackTop = stackTop;
                                                frame.savedCallOp = op;
                                                frame = calleeFrame;
                                                goto StateLoop;
                                            }
                                        }
                                        if (!(lhs is Function))
                                        {
                                            if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                            throw ScriptRuntime.notFunctionError(lhs);
                                        }
                                        Function fun = (Function)lhs;

                                        if (fun is IdFunctionObject)
                                        {
                                            IdFunctionObject ifun = (IdFunctionObject)fun;
                                            if (NativeContinuation.isContinuationConstructor(ifun))
                                            {
                                                frame.stack[stackTop] =
                                                    captureContinuation(cx, frame.parentFrame, false);
                                                goto Loop;
                                            }
                                        }

                                        Object[] outArgs = getArgsArray(stack, sDbl, stackTop + 1, indexReg);
                                        stack[stackTop] = fun.construct(cx, frame.scope, outArgs);
                                        goto Loop;
                                    }
                                case Token.TYPEOF:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.typeof1(lhs);
                                        goto Loop;
                                    }
                                case Icode_TYPEOFNAME:
                                    stack[++stackTop] = ScriptRuntime.typeofName(frame.scope, stringReg);
                                    goto Loop;
                                case Token.STRING:
                                    stack[++stackTop] = stringReg;
                                    goto Loop;
                                case Icode_SHORTNUMBER:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = getShort(iCode, frame.pc);
                                    frame.pc += 2;
                                    goto Loop;
                                case Icode_INTNUMBER:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = getInt(iCode, frame.pc);
                                    frame.pc += 4;
                                    goto Loop;
                                case Token.NUMBER:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = frame.idata.itsDoubleTable[indexReg];
                                    goto Loop;
                                case Token.NAME:
                                    stack[++stackTop] = ScriptRuntime.name(cx, frame.scope, stringReg);
                                    goto Loop;
                                case Icode_NAME_INC_DEC:
                                    stack[++stackTop] = ScriptRuntime.nameIncrDecr(frame.scope, stringReg,
                                                                                   cx, iCode[frame.pc]);
                                    ++frame.pc;
                                    goto Loop;
                                case Icode_SETCONSTVAR1:
                                    indexReg = iCode[frame.pc++];
                                    goto case Token.SETCONSTVAR;
                                // fallthrough
                                case Token.SETCONSTVAR:
                                    if (!frame.useActivation)
                                    {
                                        if ((varAttributes[indexReg] & ScriptableObject.READONLY) == 0)
                                        {
                                            throw Context.reportRuntimeError1("msg.var.redecl",
                                                                              frame.idata.argNames[indexReg]);
                                        }
                                        if ((varAttributes[indexReg] & ScriptableObject.UNINITIALIZED_CONST)
                                            != 0)
                                        {
                                            vars[indexReg] = stack[stackTop];
                                            varAttributes[indexReg] &= ~ScriptableObject.UNINITIALIZED_CONST;
                                            varDbls[indexReg] = sDbl[stackTop];
                                        }
                                    }
                                    else
                                    {
                                        Object val = stack[stackTop];
                                        if (val == DBL_MRK) val = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stringReg = frame.idata.argNames[indexReg];
                                        if (frame.scope is ConstProperties)
                                        {
                                            ConstProperties cp = (ConstProperties)frame.scope;
                                            cp.putConst(stringReg, frame.scope, val);
                                        }
                                        else
                                            throw Kit.codeBug();
                                    }
                                    goto Loop;
                                case Icode_SETVAR1:
                                    indexReg = iCode[frame.pc++];
                                    goto case Token.SETVAR;
                                // fallthrough
                                case Token.SETVAR:
                                    if (!frame.useActivation)
                                    {
                                        if ((varAttributes[indexReg] & ScriptableObject.READONLY) == 0)
                                        {
                                            vars[indexReg] = stack[stackTop];
                                            varDbls[indexReg] = sDbl[stackTop];
                                        }
                                    }
                                    else
                                    {
                                        Object val = stack[stackTop];
                                        if (val == DBL_MRK) val = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stringReg = frame.idata.argNames[indexReg];
                                        frame.scope.put(stringReg, frame.scope, val);
                                    }
                                    goto Loop;
                                case Icode_GETVAR1:
                                    indexReg = iCode[frame.pc++];
                                    goto case Token.GETVAR;
                                // fallthrough
                                case Token.GETVAR:
                                    ++stackTop;
                                    if (!frame.useActivation)
                                    {
                                        stack[stackTop] = vars[indexReg];
                                        sDbl[stackTop] = varDbls[indexReg];
                                    }
                                    else
                                    {
                                        stringReg = frame.idata.argNames[indexReg];
                                        stack[stackTop] = frame.scope.get(stringReg, frame.scope);
                                    }
                                    goto Loop;
                                case Icode_VAR_INC_DEC:
                                    {
                                        // indexReg : varindex
                                        ++stackTop;
                                        int incrDecrMask = iCode[frame.pc];
                                        if (!frame.useActivation)
                                        {
                                            stack[stackTop] = DBL_MRK;
                                            Object varValue = vars[indexReg];
                                            double d;
                                            if (varValue == DBL_MRK)
                                            {
                                                d = varDbls[indexReg];
                                            }
                                            else
                                            {
                                                d = ScriptRuntime.toNumber(varValue);
                                                vars[indexReg] = DBL_MRK;
                                            }
                                            double d2 = ((incrDecrMask & Node.DECR_FLAG) == 0)
                                                        ? d + 1.0 : d - 1.0;
                                            varDbls[indexReg] = d2;
                                            sDbl[stackTop] = ((incrDecrMask & Node.POST_FLAG) == 0) ? d2 : d;
                                        }
                                        else
                                        {
                                            String varName = frame.idata.argNames[indexReg];
                                            stack[stackTop] = ScriptRuntime.nameIncrDecr(frame.scope, varName,
                                                                                         cx, incrDecrMask);
                                        }
                                        ++frame.pc;
                                        goto Loop;
                                    }
                                case Icode_ZERO:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = 0;
                                    goto Loop;
                                case Icode_ONE:
                                    ++stackTop;
                                    stack[stackTop] = DBL_MRK;
                                    sDbl[stackTop] = 1;
                                    goto Loop;
                                case Token.NULL:
                                    stack[++stackTop] = null;
                                    goto Loop;
                                case Token.UNDEFINED:
                                
                                    stack[++stackTop] = Undefined.instance;
                                    goto Loop;
                                case Token.THIS:
                                    stack[++stackTop] = frame.thisObj;
                                    goto Loop;
                                case Token.THISFN:
                                    stack[++stackTop] = frame.fnOrScript;
                                    goto Loop;
                                case Token.FALSE:
                                    stack[++stackTop] = false;
                                    goto Loop;
                                case Token.TRUE:
                                    stack[++stackTop] = true;
                                    goto Loop;
                                case Icode_UNDEF:
                                case Icode_UnDEFINED:
                                    stack[++stackTop] = undefined;
                                    goto Loop;
                                case Token.ENTERWITH:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        frame.scope = ScriptRuntime.enterWith(lhs, cx, frame.scope);
                                        goto Loop;
                                    }
                                case Token.LEAVEWITH:
                                    frame.scope = ScriptRuntime.leaveWith(frame.scope);
                                    goto Loop;
                                case Token.CATCH_SCOPE:
                                    {
                                        // stack top: exception object
                                        // stringReg: name of exception variable
                                        // indexReg: local for exception scope
                                        --stackTop;
                                        indexReg += frame.localShift;

                                        bool afterFirstScope = (frame.idata.itsICode[frame.pc] != 0);
                                        Exception caughtException = (Exception)stack[stackTop + 1];
                                        Scriptable lastCatchScope;
                                        if (!afterFirstScope)
                                        {
                                            lastCatchScope = null;
                                        }
                                        else
                                        {
                                            lastCatchScope = (Scriptable)stack[indexReg];
                                        }
                                        stack[indexReg] = ScriptRuntime.newCatchScope(caughtException,
                                                                                      lastCatchScope, stringReg,
                                                                                      cx, frame.scope);
                                        ++frame.pc;
                                        goto Loop;
                                    }
                                case Token.ENUM_INIT_KEYS:
                                case Token.ENUM_INIT_VALUES:
                                case Token.ENUM_INIT_ARRAY:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        indexReg += frame.localShift;
                                        int enumType = op == Token.ENUM_INIT_KEYS
                                                         ? ScriptRuntime.ENUMERATE_KEYS :
                                                       op == Token.ENUM_INIT_VALUES
                                                         ? ScriptRuntime.ENUMERATE_VALUES :
                                                       ScriptRuntime.ENUMERATE_ARRAY;
                                        stack[indexReg] = ScriptRuntime.enumInit(lhs, cx, enumType);
                                        goto Loop;
                                    }
                                case Token.ENUM_NEXT:
                                case Token.ENUM_ID:
                                    {
                                        indexReg += frame.localShift;
                                        Object val = stack[indexReg];
                                        ++stackTop;
                                        stack[stackTop] = (op == Token.ENUM_NEXT)
                                                          ? (Object)ScriptRuntime.enumNext(val)
                                                          : (Object)ScriptRuntime.enumId(val, cx);
                                        goto Loop;
                                    }
                                case Token.REF_SPECIAL:
                                    {
                                        //stringReg: name of special property
                                        Object obj = stack[stackTop];
                                        if (obj == DBL_MRK) obj = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.specialRef(obj, stringReg, cx);
                                        goto Loop;
                                    }
                                case Token.REF_MEMBER:
                                    {
                                        //indexReg: flags
                                        Object elem = stack[stackTop];
                                        if (elem == DBL_MRK) elem = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object obj = stack[stackTop];
                                        if (obj == DBL_MRK) obj = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.memberRef(obj, elem, cx, indexReg);
                                        goto Loop;
                                    }
                                case Token.REF_NS_MEMBER:
                                    {
                                        //indexReg: flags
                                        Object elem = stack[stackTop];
                                        if (elem == DBL_MRK) elem = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object ns = stack[stackTop];
                                        if (ns == DBL_MRK) ns = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object obj = stack[stackTop];
                                        if (obj == DBL_MRK) obj = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.memberRef(obj, ns, elem, cx, indexReg);
                                        goto Loop;
                                    }
                                case Token.REF_NAME:
                                    {
                                        //indexReg: flags
                                        Object name = stack[stackTop];
                                        if (name == DBL_MRK) name = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.nameRef(name, cx, frame.scope,
                                                                                indexReg);
                                        goto Loop;
                                    }
                                case Token.REF_NS_NAME:
                                    {
                                        //indexReg: flags
                                        Object name = stack[stackTop];
                                        if (name == DBL_MRK) name = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        Object ns = stack[stackTop];
                                        if (ns == DBL_MRK) ns = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.nameRef(ns, name, cx, frame.scope,
                                                                                indexReg);
                                        goto Loop;
                                    }
                                case Icode_SCOPE_LOAD:
                                    indexReg += frame.localShift;
                                    frame.scope = (Scriptable)stack[indexReg];
                                    goto Loop;
                                case Icode_SCOPE_SAVE:
                                    indexReg += frame.localShift;
                                    stack[indexReg] = frame.scope;
                                    goto Loop;
                                case Icode_CLOSURE_EXPR:
                                    stack[++stackTop] = InterpretedFunction.createFunction(cx, frame.scope,
                                                                                           frame.fnOrScript,
                                                                                           indexReg);
                                    goto Loop;
                                case Icode_CLOSURE_STMT:
                                    initFunction(cx, frame.scope, frame.fnOrScript, indexReg);
                                    goto Loop;
                                case Token.REGEXP:
                                    stack[++stackTop] = frame.scriptRegExps[indexReg];
                                    goto Loop;
                                case Icode_LITERAL_NEW:
                                    // indexReg: number of values in the literal
                                    ++stackTop;
                                    stack[stackTop] = new int[indexReg];
                                    ++stackTop;
                                    stack[stackTop] = new Object[indexReg];
                                    sDbl[stackTop] = 0;
                                    goto Loop;
                                case Icode_LITERAL_SET:
                                    {
                                        Object value = stack[stackTop];
                                        if (value == DBL_MRK) value = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        int i = (int)sDbl[stackTop];
                                        ((Object[])stack[stackTop])[i] = value;
                                        sDbl[stackTop] = i + 1;
                                        goto Loop;
                                    }
                                case Icode_LITERAL_GETTER:
                                    {
                                        Object value = stack[stackTop];
                                        --stackTop;
                                        int i = (int)sDbl[stackTop];
                                        ((Object[])stack[stackTop])[i] = value;
                                        ((int[])stack[stackTop - 1])[i] = -1;
                                        sDbl[stackTop] = i + 1;
                                        goto Loop;
                                    }
                                case Icode_LITERAL_SETTER:
                                    {
                                        Object value = stack[stackTop];
                                        --stackTop;
                                        int i = (int)sDbl[stackTop];
                                        ((Object[])stack[stackTop])[i] = value;
                                        ((int[])stack[stackTop - 1])[i] = +1;
                                        sDbl[stackTop] = i + 1;
                                        goto Loop;
                                    }
                                case Token.ARRAYLIT:
                                case Icode_SPARE_ARRAYLIT:
                                case Token.OBJECTLIT:
                                    {
                                        Object[] data = (Object[])stack[stackTop];
                                        --stackTop;
                                        int[] getterSetters = (int[])stack[stackTop];
                                        Object val;
                                        if (op == Token.OBJECTLIT)
                                        {
                                            Object[] ids = (Object[])frame.idata.literalIds[indexReg];
                                            val = ScriptRuntime.newObjectLiteral(ids, data, getterSetters, cx,
                                                    frame.scope);
                                        }
                                        else
                                        {
                                            int[] skipIndexces = null;
                                            if (op == Icode_SPARE_ARRAYLIT)
                                            {
                                                skipIndexces = (int[])frame.idata.literalIds[indexReg];
                                            }
                                            val = ScriptRuntime.newArrayLiteral(data, skipIndexces, cx,
                                                                                frame.scope);
                                        }
                                        stack[stackTop] = val;
                                        goto Loop;
                                    }
                                case Icode_ENTERDQ:
                                    {
                                        Object lhs = stack[stackTop];
                                        if (lhs == DBL_MRK) lhs = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        --stackTop;
                                        frame.scope = ScriptRuntime.enterDotQuery(lhs, frame.scope);
                                        goto Loop;
                                    }
                                case Icode_LEAVEDQ:
                                    {
                                        bool valBln = stack_boolean(frame, stackTop);
                                        Object x = ScriptRuntime.updateDotQuery(valBln, frame.scope);
                                        if (x != null)
                                        {
                                            stack[stackTop] = x;
                                            frame.scope = ScriptRuntime.leaveDotQuery(frame.scope);
                                            frame.pc += 2;
                                            goto Loop;
                                        }
                                        // reset stack and PC to code after ENTERDQ
                                        --stackTop;
                                        goto jumplessRun1; ;
                                    }
                                case Token.DEFAULTNAMESPACE:
                                    {
                                        Object value = stack[stackTop];
                                        if (value == DBL_MRK) value = ScriptRuntime.wrapNumber(sDbl[stackTop]);
                                        stack[stackTop] = ScriptRuntime.setDefaultNamespace(value, cx);
                                        goto Loop;
                                    }
                                case Token.ESCXMLATTR:
                                    {
                                        Object value = stack[stackTop];
                                        if (value != DBL_MRK)
                                        {
                                            stack[stackTop] = ScriptRuntime.escapeAttributeValue(value, cx);
                                        }
                                        goto Loop;
                                    }
                                case Token.ESCXMLTEXT:
                                    {
                                        Object value = stack[stackTop];
                                        if (value != DBL_MRK)
                                        {
                                            stack[stackTop] = ScriptRuntime.escapeTextValue(value, cx);
                                        }
                                        goto Loop;
                                    }
                                case Icode_DEBUGGER:
                                    if (frame.debuggerFrame != null)
                                    {
                                        frame.debuggerFrame.onDebuggerStatement(cx);
                                    }
                                    goto Loop;
                                case Icode_LINE:
                                    frame.pcSourceLineStart = frame.pc;
                                    if (frame.debuggerFrame != null)
                                    {
                                        int line = getIndex(iCode, frame.pc);
                                        frame.debuggerFrame.onLineChange(cx, line);
                                    }
                                    frame.pc += 2;
                                    goto Loop;
                                case Icode_REG_IND_C0:
                                    indexReg = 0;
                                    goto Loop;
                                case Icode_REG_IND_C1:
                                    indexReg = 1;
                                    goto Loop;
                                case Icode_REG_IND_C2:
                                    indexReg = 2;
                                    goto Loop;
                                case Icode_REG_IND_C3:
                                    indexReg = 3;
                                    goto Loop;
                                case Icode_REG_IND_C4:
                                    indexReg = 4;
                                    goto Loop;
                                case Icode_REG_IND_C5:
                                    indexReg = 5;
                                    goto Loop;
                                case Icode_REG_IND1:
                                    indexReg = 0xFF & iCode[frame.pc];
                                    ++frame.pc;
                                    goto Loop;
                                case Icode_REG_IND2:
                                    indexReg = getIndex(iCode, frame.pc);
                                    frame.pc += 2;
                                    goto Loop;
                                case Icode_REG_IND4:
                                    indexReg = getInt(iCode, frame.pc);
                                    frame.pc += 4;
                                    goto Loop;
                                case Icode_REG_STR_C0:
                                    stringReg = strings[0];
                                    goto Loop;
                                case Icode_REG_STR_C1:
                                    stringReg = strings[1];
                                    goto Loop;
                                case Icode_REG_STR_C2:
                                    stringReg = strings[2];
                                    goto Loop;
                                case Icode_REG_STR_C3:
                                    stringReg = strings[3];
                                    goto Loop;
                                case Icode_REG_STR1:
                                    stringReg = strings[0xFF & iCode[frame.pc]];
                                    ++frame.pc;
                                    goto Loop;
                                case Icode_REG_STR2:
                                    stringReg = strings[getIndex(iCode, frame.pc)];
                                    frame.pc += 2;
                                    goto Loop;
                                case Icode_REG_STR4:
                                    stringReg = strings[getInt(iCode, frame.pc)];
                                    frame.pc += 4;
                                    goto Loop;
                                default:
                                    dumpICode(frame.idata);
                                    throw new Exception(
                                        "Unknown icode : " + op + " @ pc : " + (frame.pc - 1));
                            }  // end of interpreter switch
                        jumplessRun1: ;
                        } // end of jumplessRun label block

                        // This should be reachable only for jump implementation
                        // when pc points to encoded target offset
                        if (instructionCounting)
                        {
                            addInstructionCount(cx, frame, 2);
                        }
                        int offset = getShort(iCode, frame.pc);
                        if (offset != 0)
                        {
                            // -1 accounts for pc pointing to jump opcode + 1
                            frame.pc += offset - 1;
                        }
                        else
                        {
                            frame.pc = frame.idata.longJumps.
                                           getExistingInt(frame.pc);
                        }
                        if (instructionCounting)
                        {
                            frame.pcPrevBranch = frame.pc;
                        }
                        goto Loop;

                    } // end of Loop: for
                Loop1: ;
                    exitFrame(cx, frame, null);
                    interpreterResult = frame.result;
                    interpreterResultDbl = frame.resultDbl;
                    if (frame.parentFrame != null)
                    {
                        frame = frame.parentFrame;
                        if (frame.frozen)
                        {
                            frame = frame.cloneFrozen();
                        }
                        setCallResult(
                            frame, interpreterResult, interpreterResultDbl);
                        interpreterResult = null; // Help GC
                        goto StateLoop;
                    }
                    goto StateLoop1;

                }  // end of interpreter withoutExceptions: try
                catch (Exception ex)
                {
                    if (throwable != null)
                    {
                        // This is serious bug and it is better to track it ASAP
                        //ex.printStackTrace(System.err);
                        throw new Exception();
                    }
                    throwable = ex;
                }
            withoutExceptions1: ;
                // This should be reachable only after above catch or from
                // finally when it needs to propagate exception or from
                // explicit throw
                if (throwable == null) Kit.codeBug();

                // Exception type
                int EX_CATCH_STATE = 2; // Can execute JS catch
                int EX_FINALLY_STATE = 1; // Can execute JS finally
                int EX_NO_JS_STATE = 0; // Terminate JS execution

                int exState;
                ContinuationJump cjump1 = null;

                if (generatorState != null &&
                    generatorState.operation == NativeGenerator.GENERATOR_CLOSE &&
                    throwable == generatorState.value)
                {
                    exState = EX_FINALLY_STATE;
                }
                else if (throwable is JavaScriptException)
                {
                    exState = EX_CATCH_STATE;
                }
                else if (throwable is EcmaError)
                {
                    // an offical ECMA error object,
                    exState = EX_CATCH_STATE;
                }
                else if (throwable is EvaluatorException)
                {
                    exState = EX_CATCH_STATE;
                }
                //else if (throwable is RuntimeException)
                //{
                //    exState = cx.hasFeature(Context.FEATURE_ENHANCED_JAVA_ACCESS)
                //              ? EX_CATCH_STATE
                //              : EX_FINALLY_STATE;
                //}
                else if (throwable is Exception)
                {
                    exState = cx.hasFeature(Context.FEATURE_ENHANCED_JAVA_ACCESS)
                              ? EX_CATCH_STATE
                              : EX_NO_JS_STATE;
                }
                else if (throwable is ContinuationJump)
                {
                    // It must be ContinuationJump
                    exState = EX_FINALLY_STATE;
                    cjump1 = (ContinuationJump)throwable;
                }
                else
                {
                    exState = cx.hasFeature(Context.FEATURE_ENHANCED_JAVA_ACCESS)
                              ? EX_CATCH_STATE
                              : EX_FINALLY_STATE;
                }

                if (instructionCounting)
                {
                    try
                    {
                        addInstructionCount(cx, frame, EXCEPTION_COST);
                    }
                    catch (Exception ex)
                    {
                        throwable = ex;
                        exState = EX_FINALLY_STATE;
                    }
                    //catch (Exception ex)
                    //{
                    //    // Error from instruction counting
                    //    //     => unconditionally terminate JS
                    //    throwable = ex;
                    //    cjump1 = null;
                    //    exState = EX_NO_JS_STATE;
                    //}
                }
                if (frame.debuggerFrame != null
                    && throwable is Exception)
                {
                    // Call debugger only for RuntimeException
                    Exception rex = (Exception)throwable;
                    try
                    {
                        frame.debuggerFrame.onExceptionThrown(cx, rex);
                    }
                    catch (Exception ex)
                    {
                        // Any exception from debugger
                        //     => unconditionally terminate JS
                        throwable = ex;
                        cjump1 = null;
                        exState = EX_NO_JS_STATE;
                    }
                }

                for (; ; )
                {
                    if (exState != EX_NO_JS_STATE)
                    {
                        bool onlyFinally = (exState != EX_CATCH_STATE);
                        indexReg = getExceptionHandler(frame, onlyFinally);
                        if (indexReg >= 0)
                        {
                            // We caught an exception, restart the loop
                            // with exception pending the processing at the loop
                            // start
                            goto StateLoop;
                        }
                    }
                    // No allowed exception handlers in this frame, unwind
                    // to parent and try to look there

                    exitFrame(cx, frame, throwable);

                    frame = frame.parentFrame;
                    if (frame == null) { break; }
                    if (cjump1 != null && cjump1.branchFrame == frame)
                    {
                        // Continuation branch point was hit,
                        // restart the state loop to reenter continuation
                        indexReg = -1;
                        goto StateLoop;
                    }
                }

                // No more frames, rethrow the exception or deal with continuation
                if (cjump1 != null)
                {
                    if (cjump1.branchFrame != null)
                    {
                        // The above loop should locate the top frame
                        Kit.codeBug();
                    }
                    if (cjump1.capturedFrame != null)
                    {
                        // Restarting detached continuation
                        indexReg = -1;
                        goto StateLoop;
                    }
                    // Return continuation result to the caller
                    interpreterResult = cjump1.result;
                    interpreterResultDbl = cjump1.resultDbl;
                    throwable = null;
                }
                goto StateLoop1;

            } // end of StateLoop: for(;;)
        StateLoop1: ;
            // Do cleanups/restorations before the final return or throw

            if (cx.previousInterpreterInvocations != null
                && cx.previousInterpreterInvocations.size() != 0)
            {
                cx.lastInterpreterFrame
                    = cx.previousInterpreterInvocations.pop();
            }
            else
            {
                // It was the last interpreter frame on the stack
                cx.lastInterpreterFrame = null;
                // Force GC of the value cx.previousInterpreterInvocations
                cx.previousInterpreterInvocations = null;
            }

            if (throwable != null)
            {
                //if (throwable is RuntimeException)
                //{
                //    throw (RuntimeException)throwable;
                //}
                //else
                //{
                //    // Must be instance of Error or code bug
                //    throw (Error)throwable;
                //}
                throw new Exception();
            }

            return (interpreterResult != DBL_MRK)
                   ? interpreterResult
                   : ScriptRuntime.wrapNumber(interpreterResultDbl);
        }

        private static void initFunction(Context cx, Scriptable scope,
                                     InterpretedFunction parent, int index)
        {
            InterpretedFunction fn;
            fn = InterpretedFunction.createFunction(cx, scope, parent, index);
            ScriptRuntime.initFunction(cx, scope, fn, fn.idata.itsFunctionType,
                                       parent.idata.evalScriptFlag);
        }

        private static int getExceptionHandler(CallFrame frame,
                                          bool onlyFinally)
        {
            int[] exceptionTable = frame.idata.itsExceptionTable;
            if (exceptionTable == null)
            {
                // No exception handlers
                return -1;
            }

            // Icode switch in the interpreter increments PC immediately
            // and it is necessary to subtract 1 from the saved PC
            // to point it before the start of the next instruction.
            int pc = frame.pc - 1;

            // OPT: use binary search
            int best = -1, bestStart = 0, bestEnd = 0;
            for (int i = 0; i != exceptionTable.Length; i += EXCEPTION_SLOT_SIZE)
            {
                int start = exceptionTable[i + EXCEPTION_TRY_START_SLOT];
                int end = exceptionTable[i + EXCEPTION_TRY_END_SLOT];
                if (!(start <= pc && pc < end))
                {
                    continue;
                }
                if (onlyFinally && exceptionTable[i + EXCEPTION_TYPE_SLOT] != 1)
                {
                    continue;
                }
                if (best >= 0)
                {
                    // Since handlers always nest and they never have shared end
                    // although they can share start  it is sufficient to compare
                    // handlers ends
                    if (bestEnd < end)
                    {
                        continue;
                    }
                    // Check the above assumption
                    if (bestStart > start) Kit.codeBug(); // should be nested
                    if (bestEnd == end) Kit.codeBug();  // no ens sharing
                }
                best = i;
                bestStart = start;
                bestEnd = end;
            }
            return best;
        }

        private static NativeContinuation captureContinuation(Context cx, CallFrame frame,
        bool requireContinuationsTopFrame)
        {
            NativeContinuation c = new NativeContinuation();
            ScriptRuntime.setObjectProtoAndParent(
                c, ScriptRuntime.getTopCallScope(cx));

            // Make sure that all frames are frozen
            CallFrame x = frame;
            CallFrame outermost = frame;
            while (x != null && !x.frozen)
            {
                x.frozen = true;
                // Allow to GC unused stack space
                for (int i = x.savedStackTop + 1; i != x.stack.Length; ++i)
                {
                    // Allow to GC unused stack space
                    x.stack[i] = null;
                    x.stackAttributes[i] = ScriptableObject.EMPTY;
                }
                if (x.savedCallOp == Token.CALL)
                {
                    // the call will always overwrite the stack top with the result
                    x.stack[x.savedStackTop] = null;
                }
                else
                {
                    if (x.savedCallOp != Token.NEW) Kit.codeBug();
                    // the new operator uses stack top to store the constructed
                    // object so it shall not be cleared: see comments in
                    // setCallResult
                }
                outermost = x;
                x = x.parentFrame;
            }

            if (requireContinuationsTopFrame)
            {
                while (outermost.parentFrame != null)
                    outermost = outermost.parentFrame;

                if (!outermost.isContinuationsTopFrame)
                {
                    throw new Exception("Cannot capture continuation " +
                            "from JavaScript code not called directly by " +
                            "executeScriptWithContinuations or " +
                            "callFunctionWithContinuations");
                }
            }

            c.initImplementation(frame);
            return c;
        }

        private static Object[] getArgsArray(Object[] stack, double[] sDbl,
                                         int shift, int count)
        {
            if (count == 0)
            {
                return ScriptRuntime.emptyArgs;
            }
            Object[] args = new Object[count];
            for (int i = 0; i != count; ++i, ++shift)
            {
                Object val = stack[shift];
                if (val == UniqueTag.DOUBLE_MARK)
                {
                    val = ScriptRuntime.wrapNumber(sDbl[shift]);
                }
                args[i] = val;
            }
            return args;
        }

        private static void initFrame(Context cx, Scriptable callerScope,
                                 Scriptable thisObj,
                                 Object[] args, double[] argsDbl,
                                 int argShift, int argCount,
                                 InterpretedFunction fnOrScript,
                                 CallFrame parentFrame, CallFrame frame)
        {
            InterpreterData idata = fnOrScript.idata;

            bool useActivation = idata.itsNeedsActivation;
            DebugFrame debuggerFrame = null;
            if (cx.debugger != null)
            {
                debuggerFrame = cx.debugger.getFrame(cx, idata);
                if (debuggerFrame != null)
                {
                    useActivation = true;
                }
            }

            if (useActivation)
            {
                // 拷贝参数到数组中
                if (argsDbl != null)
                {
                    args = getArgsArray(args, argsDbl, argShift, argCount);
                }
                argShift = 0;
                argsDbl = null;
            }

            Scriptable scope;
            if (idata.itsFunctionType != 0)
            {
                if (!idata.useDynamicScope)
                {
                    scope = fnOrScript.getParentScope();
                }
                else
                {
                    scope = callerScope;
                }

                if (useActivation)
                {
                    scope = ScriptRuntime.createFunctionActivation(
                                fnOrScript, scope, args);
                }
            }
            else
            {
                scope = callerScope;
                ScriptRuntime.initScript(fnOrScript, thisObj, cx, scope,
                                         fnOrScript.idata.evalScriptFlag);
            }

            if (idata.itsNestedFunctions != null)
            {
                if (idata.itsFunctionType != 0 && !idata.itsNeedsActivation)
                    Kit.codeBug();
                for (int i = 0; i < idata.itsNestedFunctions.Length; i++)
                {
                    InterpreterData fdata = idata.itsNestedFunctions[i];
                    if (fdata.itsFunctionType == FunctionNode.FUNCTION_STATEMENT)
                    {
                        initFunction(cx, scope, fnOrScript, i);
                    }
                }
            }

            Scriptable[] scriptRegExps = null;
            if (idata.itsRegExpLiterals != null)
            {
                // Wrapped regexps for functions are stored in
                // InterpretedFunction
                // but for script which should not contain references to scope
                // the regexps re-wrapped during each script execution
                if (idata.itsFunctionType != 0)
                {
                    scriptRegExps = fnOrScript.functionRegExps;
                }
                else
                {
                    scriptRegExps = fnOrScript.createRegExpWraps(cx, scope);
                }
            }

            // Initialize args, vars, locals and stack

            int emptyStackTop = idata.itsMaxVars + idata.itsMaxLocals - 1;
            int maxFrameArray = idata.itsMaxFrameArray;
            if (maxFrameArray != emptyStackTop + idata.itsMaxStack + 1)
                Kit.codeBug();

            Object[] stack;
            int[] stackAttributes;
            double[] sDbl;
            bool stackReuse;
            if (frame.stack != null && maxFrameArray <= frame.stack.Length)
            {
                // Reuse stacks from old frame
                stackReuse = true;
                stack = frame.stack;
                stackAttributes = frame.stackAttributes;
                sDbl = frame.sDbl;
            }
            else
            {
                stackReuse = false;
                stack = new Object[maxFrameArray];
                stackAttributes = new int[maxFrameArray];
                sDbl = new double[maxFrameArray];
            }

            int varCount = idata.getParamAndVarCount();
            for (int i = 0; i < varCount; i++)
            {
                if (idata.getParamOrVarConst(i))
                    stackAttributes[i] = ScriptableObject.CONST;
            }
            int definedArgs = idata.argCount;
            if (definedArgs > argCount) { definedArgs = argCount; }

            // 填充Frame

            frame.parentFrame = parentFrame;
            frame.frameIndex = (parentFrame == null)
                               ? 0 : parentFrame.frameIndex + 1;
            if (frame.frameIndex > cx.getMaximumInterpreterStackDepth())
            {
                throw Context.reportRuntimeError("Exceeded maximum stack depth");
            }
            frame.frozen = false;

            frame.fnOrScript = fnOrScript;
            frame.idata = idata;

            frame.stack = stack;
            frame.stackAttributes = stackAttributes;
            frame.sDbl = sDbl;
            frame.varSource = frame;
            frame.localShift = idata.itsMaxVars;
            frame.emptyStackTop = emptyStackTop;

            frame.debuggerFrame = debuggerFrame;
            frame.useActivation = useActivation;

            frame.thisObj = thisObj;
            frame.scriptRegExps = scriptRegExps;


            frame.result = Undefined.instance;
            frame.pc = 0;
            frame.pcPrevBranch = 0;
            frame.pcSourceLineStart = idata.firstLinePC;
            frame.scope = scope;

            frame.savedStackTop = emptyStackTop;
            frame.savedCallOp = 0;

            Array.Copy(args, argShift, stack, 0, definedArgs);
            if (argsDbl != null)
            {
                Array.Copy(argsDbl, argShift, sDbl, 0, definedArgs);
            }
            for (int i = definedArgs; i != idata.itsMaxVars; ++i)
            {
                stack[i] = Undefined.instance;
            }
            if (stackReuse)
            {
                //清除栈，以便GC回收
                for (int i = emptyStackTop + 1; i != stack.Length; ++i)
                {
                    stack[i] = null;
                }
            }

            enterFrame(cx, frame, args, false);
        }

        private static CallFrame initFrameForApplyOrCall(Context cx, CallFrame frame,
                    int indexReg, Object[] stack, double[] sDbl, int stackTop, int op,
                    Scriptable calleeScope, IdFunctionObject ifun,
                    InterpretedFunction iApplyCallable)
        {
            Scriptable applyThis;
            if (indexReg != 0)
            {
                Object obj = stack[stackTop + 2];
                if (obj == UniqueTag.DOUBLE_MARK)
                    obj = ScriptRuntime.wrapNumber(sDbl[stackTop + 2]);
                applyThis = ScriptRuntime.toObjectOrNull(cx, obj);
            }
            else
            {
                applyThis = null;
            }
            if (applyThis == null)
            {
                // This covers the case of args[0] == (null|undefined) as well.
                applyThis = ScriptRuntime.getTopCallScope(cx);
            }
            if (op == Icode_TAIL_CALL)
            {
                exitFrame(cx, frame, null);
                frame = frame.parentFrame;
            }
            else
            {
                frame.savedStackTop = stackTop;
                frame.savedCallOp = op;
            }
            CallFrame calleeFrame = new CallFrame();
            if (BaseFunction.isApply(ifun))
            {
                Object[] callArgs = indexReg < 2 ? ScriptRuntime.emptyArgs :
                    ScriptRuntime.getApplyArguments(cx, stack[stackTop + 3]);
                initFrame(cx, calleeScope, applyThis, callArgs, null, 0,
                        callArgs.Length, iApplyCallable, frame, calleeFrame);
            }
            else
            {
                // Shift args left
                for (int i = 1; i < indexReg; ++i)
                {
                    stack[stackTop + 1 + i] = stack[stackTop + 2 + i];
                    sDbl[stackTop + 1 + i] = sDbl[stackTop + 2 + i];
                }
                int argCount = indexReg < 2 ? 0 : indexReg - 1;
                initFrame(cx, calleeScope, applyThis, stack, sDbl, stackTop + 2,
                        argCount, iApplyCallable, frame, calleeFrame);
            }

            frame = calleeFrame;
            return frame;
        }

        public static String getEncodedSource(InterpreterData idata)
        {
            if (idata.encodedSource == null)
            {
                return null;
            }
            return idata.encodedSource.Substring(idata.encodedSourceStart,
                                                 idata.encodedSourceEnd);
        }


        #region Evaluator Members

        public object compile(CompilerEnvirons compilerEnv, ScriptOrFnNode tree, string encodedSource, bool returnFunction)
        {
            this.compilerEnv = compilerEnv;
            new NodeTransformer().transform(tree);

            if (Token.printTrees)
            {
                Console.WriteLine(tree.toStringTree(tree));
            }

            if (returnFunction)
            {
                tree = tree.getFunctionNode(0);
            }

            scriptOrFn = tree;
            itsData = new InterpreterData(compilerEnv.getLanguageVersion(),
                                          scriptOrFn.getSourceName(),
                                          encodedSource);
            itsData.topLevel = true;

            if (returnFunction)
            {
                generateFunctionICode();
            }
            else
            {
                generateICodeFromTree(scriptOrFn);
            }

            return itsData;
        }

        public Function createFunctionObject(Context cx, Scriptable scope, object bytecode, object staticSecurityDomain)
        {
            if (bytecode != itsData)
            {
                Kit.codeBug();
            }
            return InterpretedFunction.createFunction(cx, scope, itsData,
                                                      staticSecurityDomain);
        }

        public Script createScriptObject(object bytecode, object staticSecurityDomain)
        {
            if (bytecode != itsData)
            {
                Kit.codeBug();
            }
            return InterpretedFunction.createScript(itsData,
                                                    staticSecurityDomain);
        }

        public void captureStackInfo(RoughJs.Error.RhinoException ex)
        {
            Context cx = Context.getCurrentContext();
            if (cx == null || cx.lastInterpreterFrame == null)
            {
                // No interpreter invocations
                ex.interpreterStackInfo = null;
                ex.interpreterLineData = null;
                return;
            }
            // has interpreter frame on the stack
            CallFrame[] array;
            if (cx.previousInterpreterInvocations == null
                || cx.previousInterpreterInvocations.size() == 0)
            {
                array = new CallFrame[1];
            }
            else
            {
                int previousCount = cx.previousInterpreterInvocations.size();
                if (cx.previousInterpreterInvocations.peek()
                    == cx.lastInterpreterFrame)
                {
                    // It can happen if exception was generated after
                    // frame was pushed to cx.previousInterpreterInvocations
                    // but before assignment to cx.lastInterpreterFrame.
                    // In this case frames has to be ignored.
                    --previousCount;
                }
                array = new CallFrame[previousCount + 1];
                cx.previousInterpreterInvocations.toArray(array);
            }
            array[array.Length - 1] = (CallFrame)cx.lastInterpreterFrame;

            int interpreterFrameCount = 0;
            for (int i = 0; i != array.Length; ++i)
            {
                interpreterFrameCount += 1 + array[i].frameIndex;
            }

            int[] linePC = new int[interpreterFrameCount];
            // Fill linePC with pc positions from all interpreter frames.
            // Start from the most nested frame
            int linePCIndex = interpreterFrameCount;
            for (int i = array.Length; i != 0; )
            {
                --i;
                CallFrame frame = array[i];
                while (frame != null)
                {
                    --linePCIndex;
                    linePC[linePCIndex] = frame.pcSourceLineStart;
                    frame = frame.parentFrame;
                }
            }
            if (linePCIndex != 0) Kit.codeBug();

            ex.interpreterStackInfo = array;
            ex.interpreterLineData = linePC;
        }

        public string getSourcePositionFromStack(Context cx, int[] linep)
        {
            CallFrame frame = (CallFrame)cx.lastInterpreterFrame;
            InterpreterData idata = frame.idata;
            if (frame.pcSourceLineStart >= 0)
            {
                linep[0] = getIndex(idata.itsICode, frame.pcSourceLineStart);
            }
            else
            {
                linep[0] = 0;
            }
            return idata.itsSourceFile;
        }

        public string getPatchedStack(RoughJs.Error.RhinoException ex, string nativeStackTrace)
        {
            throw new NotImplementedException();
        }

        public List<string> getScriptStack(RoughJs.Error.RhinoException ex)
        {
            if (ex.interpreterStackInfo == null)
            {
                return null;
            }

            List<String> list = new List<String>();
            String lineSeparator = "\n";
            //  SecurityUtilities.getSystemProperty("line.separator");

            CallFrame[] array = (CallFrame[])ex.interpreterStackInfo;
            int[] linePC = ex.interpreterLineData;
            int arrayIndex = array.Length;
            int linePCIndex = linePC.Length;
            while (arrayIndex != 0)
            {
                --arrayIndex;
                StringBuilder sb = new StringBuilder();
                CallFrame frame = array[arrayIndex];
                while (frame != null)
                {
                    if (linePCIndex == 0) Kit.codeBug();
                    --linePCIndex;
                    InterpreterData idata = frame.idata;
                    sb.Append("\tat ");
                    sb.Append(idata.itsSourceFile);
                    int pc = linePC[linePCIndex];
                    if (pc >= 0)
                    {
                        // Include line info only if available
                        sb.Append(':');
                        sb.Append(getIndex(idata.itsICode, pc));
                    }
                    if (idata.itsName != null && idata.itsName.Length != 0)
                    {
                        sb.Append(" (");
                        sb.Append(idata.itsName);
                        sb.Append(')');
                    }
                    sb.Append(lineSeparator);
                    frame = frame.parentFrame;
                }
                list.Add(sb.ToString());
            }
            return list;
        }

        public void setEvalScriptFlag(Script script)
        {
            ((InterpretedFunction)script).idata.evalScriptFlag = true;
        }


        public static Object resumeGenerator(Context cx,
                                         Scriptable scope,
                                         int operation,
                                         Object savedState,
                                         Object value)
        {
            CallFrame frame = (CallFrame)savedState;
            GeneratorState generatorState = new GeneratorState(operation, value);
            if (operation == NativeGenerator.GENERATOR_CLOSE)
            {
                try
                {
                    return interpretLoop(cx, frame, generatorState);
                }
                catch (Exception e)
                {
                    // Only propagate exceptions other than closingException
                    if (e != value)
                        throw e;
                }
                return Undefined.instance;
            }
            Object result = interpretLoop(cx, frame, generatorState);
            if (generatorState.returnedException != null)
                throw generatorState.returnedException;
            return result;
        }
        #endregion

        // For instruction counting (interpreter only)
        public int instructionCount;
        public int instructionThreshold;
    }
}
